cas 127-17-3, Pyruvic acid | Articles data

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Fluoromethylglyoxal: Synthesis and Glyoxalase I Catalyzed Product Partitioning via a Presumed Enediol Intermediate
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Kozarich, John W.,Chari, Ravi V.J.,Wu, John C.,Lawrence, Timothy L.
p. 4593 - 4595
(1981)
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Photocatalytic Conversion of Lactic Acid to Malic Acid through Pyruvic Acid in the Presence of Malic Enzyme and Semiconductor Photocatalysts
The photocatalytic fixation of CO2 in pyruvic acid to yield malic acid has been achieved in TiO2 microcrystal and CdS particle suspensions using malic enzyme as the catalyst, methyl viologen as the electron mediator and either 2-mercaptoethanol or lactic acid as the hole scavenger.The evaluation of the rate-determining step in the photocatalytic fixation reaction was made at the TiO2 microcrystal for the case of 2-mercaptoethanol as the hole scavenger.The use of lactic acid as the hole scavenger resulted in the selective photoproduction of pyruvic acid at the CdS photocatalyst, a fraction of which was then converted into malic acid by reductive CO2 fixation at the malic enzyme.However, it has been found that lactic acid causes a decrease in the catalytic activities of the enzyme, the degree depending on the relative concentrations of malic enzyme and lactic acid.
Inoue, Hiroshi,Yamachika, Mikio,Yoneyama, Hiroshi
p. 2215 - 2220
(1992)
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Lohmann,Meyerhof
p. 62
(1934)
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Oxidation of methylmalonic acid by cerium(IV). Evidence for parallel reaction pathways
The reaction between methylmalonic acid (MeMA) and Ce(IV) ion in 1 M sulfuric acid/D2SO4 has been studied by means of 1H- and 13C-NMR. When MeMA is in excess, acetic acid, hydroxymethylmalonic acid, and pyruvic acid are formed as stable end products. When Ce(IV) is in stoichiometric excess, acetic acid is the only product. Approximately 70-80% of the MeMA forms rapidly acetic acid with hydroxymethylmalonic acid and pyruvic acid as reactive intermediates. The remaining MeMA reacts along parallel pathways and forms two intermediates, which slowly convert to hydroxymethylmalonic acid and pyruvic acid, respectively.
Kvernberg, Per Olav,Hansen, Eddy W.,Pedersen, Bjorn,Rasmussen, Asbjorn,Ruoff, Peter
p. 2327 - 2331
(1997)
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Ikawa,Snell
p. 4900
(1954)
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Photooxidation of 2-Hydroxy Acids by Copper(II) Species in Aqueous Solution
Ultraviolet irradiation of aqueous lactic, glycolic, or 2-hydroxybutanoic acid in the presence of copper (II) leads to photoredox reaction to give corresponding α-keto acid, aldehyde with evolution of carbon dioxide, and the precipitate of copper (I).The mole ratio of the carbonyl products to the consumption of copper(II) is close to 0.5.Oxidative decarboxylation dominates at pH above 1 while the formation of α-keto acids favors at lower pH.The formation of α-keto acids is selectivity suppressed by the addition of free radical scavengers.Free radical oxidations of the acids with bromine atom or benzoyl radicals give exclusively α-keto acids.The reaction mechanism has been discussed.
Matsushima, Ryoka,Ichikawa, Yoshinori,Kuwabara, Katsuyuki
p. 1902 - 1907
(1980)
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Immobilization of thermotolerant intracellular enzymes on functionalized nanoporous activated carbon and application to degradation of an endocrine disruptor: kinetics, isotherm and thermodynamics studies
A bacterium, Serratia marcescens capable of degrading the endocrine disruptor, 2-nitrophloroglucinol (NPG) was isolated from tannery wastewater contaminated soil. The mixed intracellular enzymes (MICE) produced from S. marcescens were extracted and characterized. The functionalized nanoporous activated carbon matrix (FNAC) was prepared to immobilize MICE. The optimum conditions for the immobilization of MICE on FNAC were found to be time, 2.5 h; pH, 7.0; temperature, 40°C; concentration of MICE, 4 mg; particle size of FNAC, 300 μm and mass of FNAC, 1 g. The FNAC materials before and after immobilization of MICE were characterized using scanning electron microscopy, Fourier transform-infrared spectrophotometry and an X-ray diffractometer. The thermal behaviour of the free and the immobilized MICE was studied using thermogravimetric analysis. The immobilization of MICE on FNAC obeyed the Freundlich model and the immobilization process followed a pseudo second order kinetic model. MICE-FNAC matrix was used to degrade NPG in aqueous solution. The degradation of NPG by MICE-FNAC was optimum at contact time, 3 h; pH, 7.0; temperature, 40°C; concentration of NPG, 20 μM and agitation speed, 70 rpm. The degradation of NPG was found to be enhanced in the presence of Zn2+, Cu2+, Ca2+ and V3+ ions. The degradation of NPG by MICE-FNAC was studied using UV-visible, fluorescence and FTIR spectroscopy. The degradation of NPG by MICE-FNAC was confirmed using HPLC, NMR and GC-MS spectroscopy.
Saranya,Ranjitha,Sekaran
p. 66239 - 66259
(2015)
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Langenbeck,Hutschenreuter
p. 1,10
(1930)
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Crystal structure of D-serine dehydratase from Escherichia coli
D-Serine dehydratase from Escherichia coli is a member of the β-family (fold-type II) of the pyridoxal 5′-phosphate-dependent enzymes, catalyzing the conversion of D-serine to pyruvate and ammonia. The crystal structure of monomeric D-serine dehydratase has been solved to 1.97 A-resolution for an orthorhombic data set by molecular replacement. In addition, the structure was refined in a monoclinic data set to 1.55 A resolution. The structure of DSD reveals a larger pyridoxal 5′-phosphate- binding domain and a smaller domain. The active site of DSD is very similar to those of the other members of the β-family. Lys118 forms the Schiff base to PLP, the cofactor phosphate group is liganded to a tetraglycine cluster Gly279-Gly283, and the 3-hydroxyl group of PLP is liganded to Asn170 and N1 to Thr424, respectively. In the closed conformation the movement of the small domain blocks the entrance to active site of DSD. The domain movement plays an important role in the formation of the substrate recognition site and the catalysis of the enzyme. Modeling of D-serine into the active site of DSD suggests that the hydroxyl group of D-serine is coordinated to the carboxyl group of Asp238. The carboxyl oxygen of D-serine is coordinated to the hydroxyl group of Ser167 and the amide group of Leu171 (O1), whereas the O2 of the carboxyl group of D-serine is hydrogen-bonded to the hydroxyl group of Ser167 and the amide group of Thr168. A catalytic mechanism very similar to that proposed for L-serine dehydratase is discussed.
Urusova, Darya V.,Isupov, Michail N.,Antonyuk, Svetlana,Kachalova, Galina S.,Obmolova, Galina,Vagin, Alexei A.,Lebedev, Andrey A.,Burenkov, Gleb P.,Dauter, Zbigniew,Bartunik, Hans D.,Lamzin, Victor S.,Melik-Adamyan, William R.,Mueller, Thomas D.,Schnackerz, Klaus D.
p. 422 - 432
(2012)
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Exploration of Transaminase Diversity for the Oxidative Conversion of Natural Amino Acids into 2-Ketoacids and High-Value Chemicals
The use of 2-ketoacids is very common in feeds, food additives, and pharmaceuticals, and 2-ketoacids are valuable precursors for a plethora of chemically diverse compounds. Biocatalytic synthesis of 2-ketoacids starting from l-amino acids would be highly desirable because the substrates are readily available from biomass feedstock. Here, we report bioinformatic exploration of a series of aminotransferases (ATs) to achieve the desired conversion. Thermodynamic control was achieved by coupling an l-glutamate oxidation reaction in the cascade for the recycling of the amine acceptor. These enzymes were able to convert a majority of proteinogenic amino acids into the corresponding 2-ketoacids with high conversion (up to 99percent) and atom-efficiency. Furthermore, this enzyme cascade was extendable, and one-pot two-step processes were established for the synthesis of d-amino acids and N-methylated amino acids, achieving great overall conversion (up to 99percent) and high ee values (>99percent). These developed enzymatic methodologies offer convenient routes for utilizing amino acids as synthetic reagents.
Chen, Yanchun,Cui, Xuexian,Cui, Yinglu,Li, Chuijian,Li, Ruifeng,Li, Tao,Sun, Jinyuan,Wu, Bian,Zhu, Tong
p. 7950 - 7957
(2020)
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Oxidation of lactic acid by water soluble (Colloidal) manganese dioxide
Spectrophotometric method has been used to characterize water-soluble colloidal manganese dioxide obtained by the redox reaction between sodium thiosulphate and potassium permanganate in neutral aqueous medium which shows a single peak in the visible region with λmax = 425 nm. The kinetics of the oxidation of lactic acid by colloidal manganese dioxide (oxidant) has been investigated spectrophotometrically under pseudo-first-order conditions of excess lactic acid. The rate of the noncatalytic reaction pathway was slow which increased with increasing lactic acid concentration. The reaction was first-order with respect to [oxidant] as well as [lactic acid]. In presence of manganase(II) and fluoride ions, the noncatalytic path disappeared completely while the oxidation rate of autocatalytic path increased and decreased, respectively with increasing [Mn(II)] and [F-]. A mechanistic scheme in conformity with the observed kinetics has been proposed with the rate-law: v = -d[MnO2]/dt = κ1κ2[MnO2] [H+][lactic acid]T/ ([H+] Ka)(κ_1 + ≤2)
Khan, Zaheer,Raju,Akram, Mohd,Kabir-Ud-Din
p. 359 - 366
(2004)
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Characterization of two isotypes of l-threonine dehydratase from Entamoeba histolytica
The genome sequence of the enteric protozoan parasite Entamoeba histolytica suggests that amino acid catabolism plays an important role in energy metabolism. In the present study, we described kinetic and regulatory properties of catabolic l-threonine and l-serine dehydratase (TD) from E. histolytica. TD catalyses the pyridoxal phosphate-dependent dehydrative deamination of l-threonine and l-serine to ammonia and keto acids (2-oxobutyrate and pyruvate, respectively). E. histolytica possesses two TD isotypes (EhTD1-2) showing 38% mutual identity, a calculated molecular mass of 45.0 or 46.5 kDa, and an isoelectric point of 6.68 or 5.88, respectively. Only EhTD1 showed l-threonine and l-serine dehydrative deaminating activities whereas EhTD2, in which the amino acid residues involved in the substrate and cofactor binding were not conserved, was devoid of these activities. The kcat/Km value of EhTD1 was >3 fold higher for l-threonine than l-serine. EhTD1 was inhibited by l-cysteine in a competitive manner with the Ki values of 1.1 mM and 2.2 mM for l-serine and l-threonine, respectively. EhTD1 was insensitive to the allosteric activation by AMP or CMP. Three major substitutions of EhTD1 likely attribute to the insensitivity. EhTD1 was also inhibited about 50% by 20 mM 2-oxobutyrate, pyruvate, and glyoxylate; the inhibition was not, however, reversed by AMP. Together, these data showed that EhTD1 possesses unique regulatory properties distinct from other organisms and may play an important role in energy metabolism via amino acid degradation in E. histolytica.
Husain, Afzal,Jeelani, Ghulam,Sato, Dan,Ali, Vahab,Nozaki, Tomoyoshi
p. 100 - 104
(2010)
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A Convenient Electrochemical Synthesis of α-Oxoacids
The possibility of obtaining aliphatic and aromatic-α-oxoacids via the direct electrochemical carboxylation of acetyl and benzoyl chlorides has been shown for the first time.
Pokhodenko, Vitaly D.,Koshechko, Vjacheslav G.,Titov, Vladimir E.,Lopushanskaja, Victorija A.
p. 3277 - 3278
(1995)
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Kinetics and mechanism of the oxidation of some α-hydroxy acids by 2,2′-bipyridinium chlorochromate
The oxidation of glycolic, lactic, malic, and a few substituted mandelic acids by 2,2′-bipyridinium chlorochromate (BPCC) in dimethylsulphoxide leads to the formation of corresponding oxoacids. The reaction is first order each in BPCC and the hydroxy acids. The reaction is catalyzed by the hydrogen ions. The hydrogen ion dependence has the form: kobs = a + b [H+]. The oxidation of α-deuteriomandelic acid exhibited a substantial primary kinetic isotope effect (kH/kd = 5.29 at 303 K). Oxidation of p-methylmandelic acid was studied in 19 different organic solvents. The solvent effect has been analyzed by using Kamlet's and Swain's multiparametric equations. A mechanism involving a hydride ion transfer via a chromate ester is proposed.
Kumbhat, Vinita,Sharma, Pradeep K.,Banerji, Kalyan K.
p. 248 - 254
(2002)
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Mechanism of the Cl-atom-initiated Oxidation of Acetone and Hydroxyacetone in Air
The products of the Cl-atom-initiated oxidation of acetone and hydroxyacetone (CH3COCH2OH) in O2-N2 mixtures at 700 Torr and 298 K have been identified using long-path-length FTIR spectroscopy and long-path-length UV-visible diode array spectroscopy.The oxidation of acetone yields methyl glyoxal (CH3COCHO), HCHO, CO, CO2, CH3COOH, CH3OH, HCOOH and O3 as identifiable products.The data have been analysed, utilising the results of a kinetic study of the oxidation of acetone in air.The mechanism of the oxidation proceeds initially via the production of acetonylperoxy radicals (CH3COCH2O2) which are removed by their self-reaction (3), and reaction with other peroxy radicals produced by the subsequent chemistry: 2CH3COCH2O2 --> 2CH3COCH2O + O2 (3a), --> CH3COCHO + CH3COCH2OH + O2 (3b).The thermal decomposition of CH3COCH2O radicals produced in channel (3a) into CH3CO radicals and HCHO, is shown to predominate over the alternative reaction with O2, under the conditions of these experiments: CH3COCH2O + M --> CH3CO + HCHO + M (12), CH3COCH2O + O2 --> CH3COCHO + HO2 (13).Measurements of the yields of HCHO and CH3COCHO are consistent with the operation of both channels of reaction (3) and allow certain conclusions to be drawn concerning the reactions of CH3COCH2O2 with CH3O2 and CH3C(O)O2.The only detected primary organic product of the oxidation of CH3COCH2OH is CH3COCHO, formed with a yield of (100 +/- 5)percent by the following reaction sequence: Cl + CH3COCH2OH --> HCl + CH3COCHOH (4), CH3COCHOH + O2 --> CH3COCHO + HO2 (5).The concentration-time dependence of a range of secondary organic products, formed in the system was also measured.Identifiable products are CO, CO2, CH3COOH, HCHO, CH3OH, HCOOH and pyruvic acid (CH3COCOOH).These results are consistent with the presence of the CH3COCH(OH)O2 radical, formed as an intermediate in reaction (5): CH3COCH(OH)O2 CH3COCHO +HO2 (5 ).
Jenkin, Michael E.,Cox, Richard A.,Emrich, Martin,Moortgat, Geert K.
p. 2983 - 2991
(1993)
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Electroorganic synthesis in oil-in-water nanoemulsion: TEMPO-mediated electrooxidation of amphiphilic alcohols in water
Oil-in-water nanoemulsions, consisting of TEMPO, amphiphilic alcohols, and water, offer unique reaction environments for electrooxidation of the alcohols to give the corresponding carboxylic acids in good to excellent yields. Georg Thieme Verlag Stuttgart.
Yoshida, Tomonori,Kuroboshi, Manabu,Oshitani, Jun,Gotoh, Kuniaki,Tanaka, Hideo
p. 2691 - 2694
(2007)
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Keto-enol equilibria in the pyruvic acid system: Determination of the Keto-enol equilibrium constants of pyruvic acid and pyruvate anion and the acidity constant of pyruvate enol in aqueous solution
Keto-enol equilibrium constants for the pyruvic acid system in aqueous solution at 25°C were determined by Meyer halogen titration and also by another method that evaluates these constants as ratios of enolization to ketonization rate constants, KE = kE/kK. Measurements by each method were made in both acidic and basic solution, and enol required for the ketonization rate measurements was supplied by hydrolysis of a silyl derivative and also by an equilibrated DMSO solution in which the enol content is greater than it is in water. The various methods gave nicely consistent results, which nevertheless differed between acidic and basic solutions, in accord with the different states of ionization of pyruvic acid in the two media; the values obtained were pKE = 3.21 for pyruvic acid in the carboxylic acid form and pKE = 5.03 for the pyruvate ion. The latter gives a free energy change for the ketonization of pyruvate enol that is 47% of the free energy liberated by the hydrolysis of the high-energy molecule, phosphoenolpyruvate; this shows that nearly half of the high energy content of this molecule resides in its masked enol function. An acidity constant for ionization of the enol hydroxyl group of pyruvate enol, pKaE = 11.55, was also determined, and this, when combined with pKE for this species, gives pKaK = 16.58 as the acidity constant of the pyruvate ion ionizing as a carbon acid.
Chiang,Kresge,Pruszynski
p. 3103 - 3107
(1992)
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MoO3-TiO2 synergy in oxidative dehydrogenation of lactic acid to pyruvic acid
An efficient catalytic process for the oxidative dehydrogenation of biomass-derived lactic acid by earth-abundant MoO3/TiO2 mixed oxide catalysts is presented. A series of MoO3/TiO2 materials with varied MoO3 loadings were prepared and their performance in the aerobic and anaerobic conversion of lactic acid was evaluated. A strong synergistic effect between MoO3 and TiO2 components of the mixed oxide catalyst was observed. Optimum catalysts in terms of activity and pyruvic acid selectivity can be obtained by ensuring a high dispersion of MoOx species on the titania surface. Mo-oxide aggregates catalyze undesired side-reactions. XPS measurements indicate that the redox processes involving supported Mo ions are crucial for the catalytic cycle. A mechanism is proposed, in which lactic acid adsorbs onto basic sites of the titania surface and is dehydrogenated over the Mo=O acid-base pair of a vicinal tetrahedral Mo site. The catalytic cycle closes by hydrolysis of surface pyruvate and water desorption accompanied by the reduction of the Mo center, which is finally oxidized by O2 to regenerate the initial active site. Under anaerobic conditions, a less efficient catalytic cycle is established involving a bimolecular hydrogen transfer mechanism, selectively yielding propionic and pyruvic acids as the major products. The optimum catalyst is 2 wt% MoO3/TiO2 predominantly containing tetrahedral Mo species. With this catalyst the oxidative conversion of lactic acid at 200 °C proceeds with a selectivity of ca. 80% to pyruvic acid. The pyruvic acid productivity is 0.56 g g-1 h-1.
Liu, Kaituo,Huang, Xiaoming,Pidko, Evgeny A.,Hensen, Emiel J. M.
p. 3014 - 3022
(2017)
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Residue N84 of Yeast Cystathionine β-Synthase is a Determinant of Reaction Specificity
Cystathionine β-synthase (CBS) catalyzes the pyridoxal 5'-phosphate (PLP)-dependent condensation of l-serine and l-homocysteine to form l-cystathionine in the first step of the reverse transsulfuration pathway. Residue N84 of yeast CBS (yCBS), predicted to form a hydrogen bond with the hydroxyl moiety of the PLP cofactor, was mutated to alanine, aspartate and histidine. The truncated form of yCBS (ytCBS, residues 1-353) was employed in this study to eliminate any effects of the C-terminal, regulatory domain. The kcat/Kml-Ser of the N84A, N84D and N84H mutants for the β-replacement reaction is reduced by a factor of 230, 11000 and 640, respectively. Fluorescence resonance energy transfer between tryptophan residue(s) of the enzyme and the PLP cofactor, observed in the wild-type enzyme and N84A mutant, is altered in N84H and absent in N84D. PLP saturation values of 73%, 30% and 67% were observed for the alanine, aspartate and histidine mutants, respectively, compared to 98% for the wild-type enzyme. A marginal β-elimination activity was detected for N84D (kcat/Kml-Ser = 0.23 ± 0.02 M-1 s-1) and N84H (kcat/Kml-Ser = 0.34 ± 0.06 M-1 s-1), in contrast with wild-type ytCBS and the N84A mutant, which do not catalyze this reaction. The ytCBS-N84D enzyme is also inactivated upon incubation with l-serine, via an aminoacrylate-mediated mechanism. These results demonstrate that residue N84 is essential in maintaining the orientation of the pyridine ring of the PLP cofactor and the equilibrium between the open and closed conformations of the active site.
Lodha, Pratik H.,Hopwood, Emily M.S.,Manders, Adrienne L.,Aitken, Susan M.
p. 1424 - 1431
(2010)
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Sustainable production of pyruvic acid: Oxidative dehydrogenation of lactic acid over the FeMoO/P catalyst
Fe-Mo bimetallic oxide catalysts doped with elemental P (FeMoO/P) were synthesized using a hydrothermal method, followed by calcination in air. The resultant catalysts were used to catalyze the oxidative dehydrogenation of lactic acid to pyruvic acid using air as an oxidant. UV-Vis characterization revealed that Fe2O3 was highly dispersed on the surface of MoO3 for the FeMoO/P sample due to the enhanced band gap energy. The FeMoO/P sample showed distinct diffraction lines of MoO3, while the diffraction of the typical (011) line slightly shifted to a higher 2 theta value. This indicated the incorporation of Fe3+ into the MoO3 lattice, forming a surface substituted Fe-Ox-Mo solid solution. Furthermore, the other characterization techniques such as XPS and H2-TPR disclosed a strong interaction between Fe2O3 and MoO3 by binding energy shift and reducible peak change, respectively. The enhanced oxidizability of Fe species is responsible for the activation of the α-OH group in the lactic acid molecule, transferring hydrogen to the adjacent FeOx site to achieve a crucial step for the oxidative dehydrogenation of lactic acid. For comparison, the Fe-Mo bimetallic oxide catalyst offered far better activity than its corresponding monometallic oxide/physically mixed oxide due to the increasing oxidizability of FeMoO/P by electron transfer between Fe and Mo species. On-line analysis of the tail gas revealed that no hydrogen was detected, precluding direct dehydrogenation of lactic acid to form pyruvic acid during the catalytic reaction. Furthermore, the experimental results in the absence of O2, replaced by N2, showed that a small amount of pyruvic acid formed, and it gradually decreased with time on stream, demonstrating lattice oxygen as an active species for the oxidative dehydrogenation of lactic acid. Encouragingly, the oxidative dehydrogenation reaction of lactic acid over the FeMoO/P catalyst proceeded efficiently at around 60 h on stream and with an excellent selectivity (>70%).
Yin, Chunyu,Li, Xinli,Chen, Zhi,Peng, Yanli,Wei, Song,Tang, Congming,Zou, Weixin,Dong, Lin
p. 5884 - 5894
(2020)
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Photocatalytic reversible amination of α-keto acids on a ZnS surface: Implications for the prebiotic metabolism
We report the enzyme-like reversible amination of four intermediates pertinent to the reductive tricarboxylic acid cycle on a photo-irradiated surface of mineral sphalerite (ZnS). Given its prevalence in the waters of early Earth, we suggest that the mineral-based photochemistry might have catalyzed the homeostasis of prebiotic metabolic systems.
Wang, Wei,Li, Qiliang,Yang, Bin,Liu, Xiaoyang,Yang, Yanqiang,Su, Wenhui
p. 2146 - 2148
(2012)
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Model reactions for enzymatic catalysis. 3. A glutamate-pyruvate-transaminase model
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Gebert,von Kerekjarto
p. 1327 - 1330
(1969)
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Rate constants for the reactions of methyl vinyl ketone, methacrolein, methacrylic acid, and acrylic acid with ozone
Rate constants for the reaction of ozone with methylvinyl ketone (H2C=CHC(O)CH3), methacrolein (H2C=C(CH3)CHO), methacrylic acid (H2C=C(CH3)C(O)OH), and acrylic acid (H2C=CHC(O)OH) were measured at room temperature (296 ± 2 K) in the presence of a sufficient amount of cyclohexane to scavenge OH-radicals. Results from pseudo-first-order experiments in the presence of excess ozone were found not to be consistent with relative rate measurements. It appeared that the formation of the so-called Criegee-intermediates leads to an enhanced decrease in the concentration of the two organic acids investigated. It is shown that the presence of formic acid, which is known to react efficiently with Criegee-intermediates, diminishes the observed removal rate of the organic acids. The rate constant for the reaction of ozone with the unsaturated carbonyl compounds methylvinyl ketone and methacrolein was found not to be influenced by the addition of formic acid. Rate constants for the reaction of ozone determined in the presence of excess formic acid are (in cm3 molecule-1 s-1): methylvinyl ketone (5.4 ± 0.6) × 10-18; methacrolein (1.3 ± 0.14) × 10-18; methacrylic acid (4.1 ± 0.4) × 10-18; and acrylic acid (0.65 ± 0.13) × 10-18. Results are found to be consistent with the Criegee mechanism of the gas-phase ozonolysis.
Neeb, Peter,Kolloff, Antje,Koch, Stephan,Moortgat, Geert K.
p. 769 - 776
(1998)
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Serine racemases from barley, Hordeum vulgare L., and other plant species represent a distinct eukaryotic group: Gene cloning and recombinant protein characterization
Several d-amino acids have been identified in plants. However, the biosynthetic pathway to them is unclear. In this study, we cloned and sequenced a cDNA encoding a serine racemase from barley which contained an open reading frame encoding 337 amino acid residues. The deduced amino acid sequence showed significant identity to plant and mammalian serine racemases and contained conserved pyridoxal 5-phosphate (PLP)-binding lysine and PLP-interacting amino acid residues. The purified gene product catalyzed not only racemization of serine but also dehydration of serine to pyruvate. The enzyme requires PLP and divalent cations such as Ca2+, Mg2+, or Mn2+, but not ATP, whereas mammalian serine racemase activity is increased by ATP. In addition to the results regarding the effect of ATP on enzyme activity and the phylogenetic analysis of eukaryotic serine racemases, the antiserum against Arabidopsis serine racemase did not form a precipitate with barley and rice serine racemases. This suggests that plant serine racemases represent a distinct group in the eukaryotic serine racemase family and can be clustered into monocot and dicot types.
Fujitani, Yoshiyuki,Horiuchi, Terumi,Ito, Kazutoshi,Sugimoto, Manabu
p. 1530 - 1536
(2007)
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Novel substrate specificity of designer 3-isopropylmalate dehydrogenase derived from Thermus thermophilus HB8
Redesigning of an enzyme for a new catalytic reaction and modified substrate specificity was exploited with 3-isopropylmalate dehydrogenase (IPMDH). Point-mutation on Gly-89, which is not in the catalytic site but near it, was done by changing it to Ala, Ser, Val, and Pro, and all the mutations changed the substrate specificity. The mutant enzymes showed higher catalytic efficiency (kcat/Km) than the native IPMDH when malate was used as a substrate instead of 3-isopropylmalate. More interestingly, an additional insertion of Gly between Gly-89 and Leu-90 significantly altered the substrate-specificity, although the overall catalytic activity was decreased. Particularly, this mutant turned out to efficiently accept D-lactic acid, which was not accepted as a substrate by wild-type IPMDH at all. These results demonstrate the opportunity for creating novel enzymes by modification of amino acid residues that do not directly participate in catalysis, or by insertion of additional residues.
Fujita, Masaaki,Tamegai, Hideyuki,Eguchi, Tadashi,Kakinuma, Katsumi
p. 2695 - 2700
(2001)
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Metzler
p. 485,488
(1957)
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Hamilton,Revesz
p. 2069
(1966)
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Kiessling
(1936)
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Photoinitiated synthesis of self-assembled vesicles
The aqueous photochemistry of 2-oxooctanoic acid (a single-tailed surfactant) results in the synthesis of a double-tailed surfactant product followed by spontaneous self-assembly into vesicles. The photochemical mechanism is detailed here, and the reaction products are identified using mass spectrometry. Then, the self-assembled vesicles are characterized using dynamic light scattering, fluorescence microscopy, and NMR. Further, their stability over time and in the presence of MgCl2 salt is demonstrated. This work contributes to membrane evolution through the provision of a prebiotic route for the synthesis of plausible membrane components and subsequent self-assembly of a primitive enclosure.
Griffith, Elizabeth C.,Rapf, Rebecca J.,Shoemaker, Richard K.,Carpenter, Barry K.,Vaida, Veronica
p. 3784 - 3787
(2014)
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Catalytic oxidative dehydrogenation of malic acid to oxaloacetic acid
Here we report the oxidative dehydrogenation of malic acid to oxaloacetic acid, a key precursor in the fabrication of amino acids, over Pt-Bi/C catalysts. Under optimized conditions, we discovered that OAA was selectively produced with up to 60% conversion (i.e. 60% yield). The recurrent unwanted decarboxylation of OAA to pyruvic acid was circumvented by successfully conducting the catalytic reaction at 25 °C. A comparison with the classical Fenton oxidation reaction is discussed.
Drif, Asmaa,Pineda, Antonio,Morvan, Didier,Belliere-Baca, Virginie,De Oliveira Vigier, Karine,Jér?me, Fran?ois
p. 4604 - 4608
(2019)
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Biosynthesis of Rhizocticins, Antifungal Phosphonate Oligopeptides Produced by Bacillus subtilis ATCC6633
Rhizocticins are phosphonate oligopeptide antibiotics containing the C-terminal nonproteinogenic amino acid (Z)-l-2-amino-5-phosphono-3-pentenoic acid (APPA). Here we report the identification and characterization of the rhizocticin biosynthetic gene cluster (rhi) in Bacillus subtilis ATCC6633. Rhizocticin B was heterologously produced in the nonproducer strain Bacillus subtilis 168. A biosynthetic pathway is proposed on the basis of bioinformatics analysis of the rhi genes. One of the steps during the biosynthesis of APPA is an unusual aldol reaction between phosphonoacetaldehyde and oxaloacetate catalyzed by an aldolase homolog RhiG. Recombinant RhiG was prepared, and the product of an in vitro enzymatic conversion was characterized. Access to this intermediate allows for biochemical characterization of subsequent steps in the pathway.
Borisova, Svetlana A.,Circello, Benjamin T.,Zhang, Jun Kai,van der Donk, Wilfred A.,Metcalf, William W.
p. 28 - 37
(2010)
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E2-elimination in the decomposition of N-bromoamino acid anions
The kinetics of oxidation of eight structurally different amino acids by hypobromite ion (BrO-) in the presence of hydroxide ion has been studied. The reactions proceed through the rapid formation of N-bromoamino acid anion which then decomposes in the rate-limiting step. The decomposition of N-bromoamino acid anions is found to proceed through an unimolecular and a base-catalyzed reaction. The large negative values of ΔS? and the products formed suggest that the hydroxide ion-catalyzed reactions proceed through an E2 mechanism. N-Bromoamino acid anion gives an absorption spectrum with λmax at ≈290 nm.
Ramachandran,Easwaramoorthy,Vasanthkumar
p. 4336 - 4341
(1996)
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Evans,Leermakers
p. 1840
(1968)
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Effect of Semiconductor on Photocatalytic Decomposition of Lactic Acid
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Harada, H.,Sakata, T.,Ueda, T.
p. 1773 - 1774
(1985)
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Oxidative dehydrogenation of lactic acid to pyruvic acid over Pb-Pt bimetallic supported on carbon materials
Various carbon materials, including activated carbon, flake graphite, carbon black and multiwall carbon nanotubes, were adopted as supports for lead-promoted platinum catalysts in the investigation of aqueous-phase oxidative dehydrogenation of lactic acid to produce pyruvic acid. Among them, the nanoscale 3Pb-1Pt/carbon black catalyst showed the highest TOF (769?h?1) and yielded 60% pyruvic acid within 20?min under mild conditions. N2adsorption, Raman spectroscopy, thermogravimetry, SEM, TEM and XPS were performed to investigate their different structures, graphitization degrees, metal particle sizes and surface oxidation states. Under the current conditions, smaller support particle size is essential for the enhanced lactic acid transformation rate by favoring the diffusion of reactants; less graphitic structure of catalyst is also beneficial by improving metal particle dispersion and facilitating the exposure of metals.
Zhang, Chen,Wang, Tao,Ding, Yunjie
p. 59 - 65
(2017)
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Enantioselective Catalysis by Artificial Tryptophan Synthase Formed with Functionalized Bilayer Membrane
A functionalized bilayer membrane, composed of a cationic peptide lipid having a L-histidyl residue, a hydrophobic pyridoxal derivative, and copper(II) ions, catalyzed the β-replacement reaction of serine with indole to afford tryptophan in a significant enantiomeric excess of the D-isomer.
Murakami, Yukito,Hisaeda, Yoshio,Nakamura, Koichiro,Kikuchi, Jun-ichi
p. 1765 - 1768
(1990)
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A simple and sensitive detection of glutamic-pyruvic transaminase activity based on fluorescence quenching of bovine serum albumin
It is well known that Cu(ii) can coordinate with l-alanine (Cu-Ala), which can be destroyed through the addition of glutamic-pyruvic transaminase (GPT) since GPT can effectively catalyze the conversion of l-alanine into keto-acetic acid. As a result, the free Cu(ii) ion can combine with bovine serum albumin (BSA) and in turn quench the fluorescence of BSA. In this context, a simple and sensitive GPT activity detection via fluorescence quenching method has been developed. The fluorescence intensity of the system shows a linear relationship with the GPT concentration in the range of 5 and 400 U L-1 with a detection limit down to 3 U L-1 (S/N = 3). Avoiding any labels or complicated operations, this cost-effective and convenient method holds the potential for the rapid diagnosis of GPT-related diseases.
Chen, Miao,Rong, Liya,Chen, Xiaoqing
p. 103557 - 103562
(2015)
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Metal ion inhibition of nonenzymatic pyridoxal phosphate catalyzed decarboxylation and transamination
Nonenzymatic pyridoxal phosphate (PLP) catalyzed decarboxylations and transaminations have been revisited experimentally. Metal ions are known to catalyze a variety of PLP-dependent reactions in solution, including transamination. It is demonstrated here that the rate accelerations previously observed are due solely to enhancement of Schiff base formation under subsaturating conditions. A variety of metal ions were tested for their effects on the reactivity of the 2-methyl-2-aminomalonate Schiff bases. All were found to have either no effect or a small inhibitory one. The effects of Al3+ were studied in detail with the Schiff bases of 2-methyl-2-aminomalonate, 2-aminoisobutyrate, alanine, and ethylamine. The decarboxylation of 2-methyl-2-aminomalonate is unaffected by metalation with Al3+, while the decarboxylation of 2-aminoisobutyrate is inhibited 125-fold. The transamination reaction of ethylamine is 75-fold slower than that of alanine. Ethylamine transamination is inhibited 4-fold by Al3+ metalation, while alanine transamination is inhibited only 1.3-fold. Metal ion inhibition of Schiff base reactivity suggests a simple explanation for the lack of known PLP dependent enzymes that make direct mechanistic use of metal ions. A comparison of enzyme catalyzed, PLP catalyzed, and uncatalyzed reactions shows that PLP dependent decarboxylases are among the best known biological rate enhancers: decarboxylation occurs 1018-fold faster on the enzyme surface than it does free in solution. PLP itself provides the lion's share of the catalytic efficiency of the holoenzyme: at pH 8, free PLP catalyzes 2-aminoisobutyrate decarboxylation by ～1010-fold, with the enzyme contributing an additional ～108-fold.
Zabinski,Toney
p. 193 - 198
(2001)
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Enzymatic synthesis of pyruvic acid from acetaldehyde and carbon dioxide
A new enzymatic synthesis of pyruvic acid from acetaldehyde and carbon dioxide has been developed.
Miyazaki,Shibue,Ogino,Nakamura,Maeda
p. 1800 - 1801
(2001)
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A model system for cysteine desulphydrase action: pyridoxal phosphate-vanadium.
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BERGEL,BRAY,HARRAP
p. 1654 - 1655
(1958)
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Boeeseken,Jakobs
p. 811
(1936)
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Electrochemical Fixation of CO2 in Acetyl-coenzyme A to Yield Pyruvic Acid Using Pyruvate Dehydrogenase Complexes as an Electrocatalyst
Electrochemical fixation of CO2 in acetyl-coenzyme A has successfully been accomplished by using pyruvate dehydrogenase complex as an electrocatalyst.The production of pyruvic acid was enhanced when coenzyme A, which was a byproduct in the pyruvic acid production, was converted to the substrate in situ in the electrolytic cell with assistance of acetyl phosphate and phosphotransacetylase.
Kuwabata, Susumu,Morishita, Nobuyasu,Yoneyama, Hiroshi
p. 1151 - 1154
(1990)
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Brockmann,Stier
p. 413
(1948)
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Bioactivation of chemopreventive selenocysteine Se-conjugates and related amino acids by amino acid oxidases novel route of metabolism of selenoamino acids
Several selenocysteine Se-conjugates have been shown to possess potent chemopreventive activity in animal models for chemical carcinogenesis. As a mechanism of action, β-elimination reactions to form chemopreventive selenols, ammonia, and pyruvate has been proposed. The enzymes involved in these β-elimination reactions, however, have been partially elucidated. Next to cysteine conjugate β-lyases, as yet unidentified non-pyridoxal-5′-phosphate-dependent enzymes also appear to be involved in cytosolic β-elimination reactions. In the present study, it was investigated whether amino acid oxidases contribute to the bioactivation of selenocysteine Se-conjugates. Using purified L-amino acid oxidase from Crotalus adamanteus as a model enzyme, significant β-elimination activities were indeed observed upon incubation with Se-methylselenocysteine (Km, 195 μM; kcat, 48 min-1), Se-allylselenocysteine (Km, 608 μM; kcat, 34 min-1), Se-phenylselenocysteine (Km, 107 μM; kcat, 57 min-1) and Se-benzylselenocysteine (Km, 59 μM; kcat, 13 min-1). For all selenocysteine Se-conjugates tested, the rate of pyruvate formation was comparable to that of hydrogen peroxide, one of the products of oxidative deamination. The fact that addition of catalase did not alter pyruvate formation indicated that the β-elimination reaction observed was not mediated by selenoxidation/syn-elimination due to the hydrogen peroxide formed via the oxidative deamination pathway. Using D-amino acid oxidase from porcine kidney and D-SeCys conjugates similar results were obtained. To delineate whether mammalian L-amino acid oxidases are also able to catalyze β-elimination of selenocysteine Se-conjugates, rat renal cytosol was fractionated and screened for β-elimination and oxidative deamination activities. One of the fractions isolated displayed oxidative deamination activity with several amino acids and cysteine S-conjugates. With selenocysteine Se-conjugates as substrates, however, this fraction displayed both oxidative deamination and β-elimination activities, when incubated in the presence of aminoxyacetic acid to block contribution of pyridoxal-5′-phosphate-dependent enzymes. The potential significance of this novel bioactivation route for the chemopreventive activity of selenocysteine Se-conjugates is discussed.
Rooseboom,Vermeulen,Van Hemert,Commandeur
p. 996 - 1005
(2001)
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Utilizing in situ spectroscopic tools to monitor ketal deprotection processes
The use of protection groups to shield a functional group during a synthesis is employed throughout many reactions and organic syntheses. The role of a protection group can be vital to the success of a reaction, as well as increase reaction yield and selectivity. Although much work has been done to investigate the addition of a protection group, the removal of the protection group is just as important – however, there is a lack of methods employed within the literature for monitoring the removal of a protection group in real time. In this work, the process of removing, or deprotecting, a ketal protecting group is investigated. Process analytical technology tools are incorporated for in situ analysis of the deprotection reaction of a small molecule model compound. Specifically, Raman spectroscopy and Fourier transform infrared spectroscopy show that characteristic bands can be used to track the decrease of the reactant and the increase of the expected products over time. To the best of our knowledge, this is the first report of process analytical technology being used to monitor a ketal deprotection reaction in real time. This information can be capitalized on in the future for understanding and optimizing pharmaceutically-relevant deprotection processes and downstream reactions.
Ralbovsky, Nicole M.,Lomont, Justin P.,Ruccolo, Serge,Konietzko, Janelle,McHugh, Patrick M.,Wang, Sheng-Ching,Mangion, Ian,Smith, Joseph P.
(2021/12/08)

From Tryptophan to Toxin: Nature's Convergent Biosynthetic Strategy to Aetokthonotoxin
Aetokthonotoxin (AETX) is a cyanobacterial neurotoxin that causes vacuolar myelinopathy, a neurological disease that is particularly deadly to bald eagles in the United States. The recently characterized AETX is structurally unique among cyanotoxins and is composed of a pentabrominated biindole nitrile. Herein we report the discovery of an efficient, five-enzyme biosynthetic pathway that the freshwater cyanobacterium Aetokthonos hydrillicola uses to convert two molecules of tryptophan to AETX. We demonstrate that the biosynthetic pathway follows a convergent route in which two functionalized indole monomers are assembled and then reunited by biaryl coupling catalyzed by the cytochrome P450 AetB. Our results revealed enzymes with novel biochemical functions, including the single-component flavin-dependent tryptophan halogenase AetF and the iron-dependent nitrile synthase AetD.
Adak, Sanjoy,Lukowski, April L.,Sch?fer, Rebecca J. B.,Moore, Bradley S.
supporting information
p. 2861 - 2866
(2022/02/23)

The facet-regulated oxidative dehydrogenation of lactic acid to pyruvic acid on α-Fe2O3
We propose a highly active α-Fe2O3 catalyst for the oxidative dehydrogenation of lactic acid to value-added pyruvic acid in air. The activity is determined by the utilized crystal face, due to the different adsorption energies of lactic acid molecules on different exposed planes. Furthermore, Fe sites show more preferential adsorption than crystal O sites.
Yin, Chunyu,Li, Xinli,Dai, Yunsheng,Chen, Zhi,Yang, Dingfeng,Liu, Ruixue,Zou, Weixin,Tang, Congming,Dong, Lin
supporting information
p. 328 - 332
(2021/01/29)

Photoinduced homolytic decarboxylative acylation/cyclization of unactivated alkenes with α-keto acid under external oxidant and photocatalyst free conditions: access to quinazolinone derivatives
A novel and green strategy for the synthesis of acylated quinazolinone derivativesviaphoto-induced decarboxylative cascade radical acylation/cyclization of quinazolinone bearing unactivated alkenes has been developed. The protocol provides a novel route to access acyl radicals from α-keto acids through a self-catalyzed energy transfer process. Most importantly, the reaction proceeded smoothly without any external photocatalyst, additive or oxidant, and could be easily scaled-up in flow conditions with sunlight irradiation.
Sun, Bin,Shi, Rongcheng,Zhang, Kesheng,Tang, Xiaoli,Shi, Xiayue,Xu, Jiayun,Yang, Jin,Jin, Can
supporting information
p. 6050 - 6053
(2021/06/21)

Novel peptidomimetic peptide deformylase (PDF) inhibitors of Mycobacterium tuberculosis
Emergence of MDR-TB and XDR-TB led to the failure of available anti-tubercular drugs. In order to explore, identify and develop new anti-tubercular drugs, novel peptidomimetic series of Mtb–peptide deformylase (PDF) inhibitors was designed and synthesized. In vitro antimycobacterial potential of compounds was established by screening of compounds against Mycobacterium tuberculosis H37Rv strain using MABA. Among them, ester series of compounds 4a, 4b, 4c, 4d, and 4e were found most active, with compound 4c being highly active and exhibiting minimum inhibitory concentration of 6.25?μg/ml against M.?tb H37Rv strain. Additionally, the compounds were docked to determine the probable binding interactions and understand the mechanism of action of most active molecules on Mtb-peptide deformylase (PDF), which is involved in the mycobacterium protein synthesis.
Gokhale, Kunal M.,Telvekar, Vikas N.
p. 148 - 156
(2020/08/26)

Effect of physicochemical parameters on the stability and activity of garlic alliinase and its use for in-situ allicin synthesis
Garlic is a well-known example of natural self-defence system consisting of an inactive substrate (alliin) and enzyme (alliinase) which, when combined, produce highly antimicrobial allicin. Increase of alliinase stability and its activity are of paramount importance in various applications relying on its use for in-situ synthesis of allicin or its analogues, e.g., pulmonary drug delivery, treatment of superficial injuries, or urease inhibitors in fertilizers. Here, we discuss the effect of temperature, pH, buffers, salts, and additives, i.e. antioxidants, chelating agents, reducing agents and cosolvents, on the stability and the activity of alliinase extracted from garlic. The effects of the storage temperature and relative humidity on the stability of lyophilized alliinase was demonstrated. A combination of the short half-life, high reactivity and non-specificity to particular proteins are reasons most bacteria cannot deal with allicin's mode of action and develop effective defence mechanism, which could be the key to sustainable drug design addressing serious problems with escalating emergence of multidrug-resistant (MDR) bacterial strains.
Janska, Petra,Knejzlík, Zdenek,Perumal, Ayyappasamy Sudalaiyadum,Jurok, Radek,Tokarova, Viola,Nicolau, Dan V.,Tepanek, FrantisekS,Kaspar, Ondrej
(2021/03/26)

Transfer hydrogenation of CO2into formaldehyde from aqueous glycerol heterogeneously catalyzed by Ru bound to LDH
Aqueous glycerol was used in this study as a liquid-phase hydrogen source for the hydrogenation of CO2. It was found that hydrogen could be efficiently evolved from aqueous glycerol upon highly dispersed Ru on layered double hydroxide (LDH), inducing the transformation of CO2 into formaldehyde under base-free conditions at low temperature.
Deng, Lidan,Liu, Xiaowei,Xu, Jie,Zhou, Zijian,Feng, Shixiang,Wang, Zheng,Xu, Minghou
supporting information
p. 5167 - 5170
(2021/05/31)

Plasmonic Oxidation of Glycerol Using Au/TiO2 Catalysts Prepared by Sol-Immobilisation
Abstract: Au nanoparticles supported on P25 TiO2 (Au/TiO2) were prepared by a facile sol-immobilisation method and investigated for the surface plasmon-assisted glycerol oxidation under base-free conditions. The Au/TiO2 samples were characterized by UV–vis spectroscopy and transmission electron microscopy. Catalysts were prepared using polyvinyl alcohol as stabiliser as well as in the absence of polymer stabiliser. Both the conversion and the reaction selectivity are affected by the plasmon-assisted oxidation and there is an interplay between the presence of the stabiliser and the Au nanoparticle size. Graphic Abstract: [Figure not available: see fulltext.].
Abis, Laura,Dimitratos, Nikolaos,Sankar, Meenakshisundaram,Freakley, Simon J.,Hutchings, Graham J.
p. 49 - 55
(2019/11/03)

Two-Dimensional Tin Selenide (SnSe) Nanosheets Capable of Mimicking Key Dehydrogenases in Cellular Metabolism
While dehydrogenases play crucial roles in tricarboxylic acid (TCA) cycle of cell metabolism, which are extensively explored for biomedical and chemical engineering uses, it is a big challenge to overcome the shortcomings (low stability and high costs) of recombinant dehydrogenases. Herein, it is shown that two-dimensional (2D) SnSe is capable of mimicking native dehydrogenases to efficiently catalyze hydrogen transfer from 1-(R)-2-(R′)-ethanol groups. In contrary to susceptible native dehydrogenases, lactic dehydrogenase (LDH) for instance, SnSe is extremely tolerant to reaction condition changes (pH, temperature, and organic solvents) and displays extraordinary reusable capability. Structure–activity analysis indicates that the single-atom structure, Sn vacancy, and hydrogen binding affinity of SnSe may be responsible for their catalytic activity. Overall, this is the first report of a 2D SnSe nanozyme to mimic key dehydrogenases in cell metabolism.
Gao, Meng,Wang, Zhenzhen,Zheng, Huizhen,Wang, Li,Xu, Shujuan,Liu, Xi,Li, Wei,Pan, Yanxia,Wang, Weili,Cai, Xiaoming,Wu, Ren'an,Gao, Xingfa,Li, Ruibin
supporting information
p. 3618 - 3623
(2020/02/13)

Self-Exfoliated Synthesis of Transition Metal Phosphate Nanolayers for Selective Aerobic Oxidation of Ethyl Lactate to Ethyl Pyruvate
Two-dimensional (2D) transition metal nanosheets are promising catalysts because of the enhanced exposure of the active species compared to their 3D counterparts. Here, we report a simple, scalable, and reproducible strategy to prepare 2D phosphate nanosheets by forming a layered structure in situ from phytic acid (PTA) and transition metal precursors. Controlled combustion of the organic groups of PTA results in interlayer carbon, which keeps the layers apart during the formation of phosphate, and the removal of this carbon results in ultrathin nanosheets with controllable layers. Applying this concept to vanadyl phosphate synthesis, we show that the method yields 2D ultrathin nanosheets of the orthorhombic β-form, exposing abundant V4+/V5+ redox sites and oxygen vacancies. We demonstrate the high catalytic activity of this material in the vapor-phase aerobic oxidation of ethyl lactate to ethyl pyruvate. Importantly, these β-VOPO4 compounds do not get hydrated, thereby reducing the competing hydrolysis reaction by water byproducts. The result has superior selectivity to ethyl pyruvate compared to analogous vanadyl phosphates. The catalysts are highly stable, maintaining a steady-state conversion of ～90% (with >80% selectivity) for at least 80 h on stream. This "self-exfoliated" synthesis protocol opens opportunities for preparing structurally diverse metal phosphates for catalysis and other applications.
Li, Lain-Jong,Oulego, Paula,Rothenberg, Gadi,Sharma, Sandeep K.,Shiju, N. Raveendran,Yang, Xiu-Lin,Zhang, Wei
p. 3958 - 3967
(2020/05/05)

Expanding the repertoire of nitrilases with broad substrate specificity and high substrate tolerance for biocatalytic applications
Enzymatic conversion of nitriles to carboxylic acids by nitrilases has gained significance in the green synthesis of several pharmaceutical precursors and fine chemicals. Although nitrilases from several sources have been characterized, there exists a scope for identifying broad spectrum nitrilases exhibiting higher substrate tolerance and better thermostability to develop industrially relevant biocatalytic processes. Through genome mining, we have identified nine novel nitrilase sequences from bacteria and evaluated their activity on a broad spectrum of 23 industrially relevant nitrile substrates. Nitrilases from Zobellia galactanivorans, Achromobacter insolitus and Cupriavidus necator were highly active on varying classes of nitriles and applied as whole cell biocatalysts in lab scale processes. Z. galactanivorans nitrilase could convert 4-cyanopyridine to achieve yields of 1.79 M isonicotinic acid within 3 h via fed-batch substrate addition. The nitrilase from A. insolitus could hydrolyze 630 mM iminodiacetonitrile at a fast rate, effecting 86 % conversion to iminodiacetic acid within 1 h. The arylaliphatic nitrilase from C. necator catalysed enantioselective hydrolysis of 740 mM mandelonitrile to (R)-mandelic acid in 4 h. Significantly high product yields suggest that these enzymes would be promising additions to the suite of nitrilases for upscale biocatalytic application.
Rayavarapu, Pratima,Shah, Shikha,Sunder, Avinash Vellore,Wangikar, Pramod P.
p. 289 - 296
(2020/05/18)

Electrochemical oxidation of amoxicillin on carbon nanotubes and carbon nanotube supported metal modified electrodes
The electrolysis of amoxicillin (AMX) was carried out on CNT, Pt/CNT and Ru/CNT modified electrodes based on Carbon Toray in 0.1 M NaOH, 0.1 M NaCl and 0.1 M Na2CO3/NaHCO3 buffer (pH 10) media with the aim of studying the significance of two factors, electrode material and pH, on the oxidative degradation and mineralization of AMX. For this purpose, the electrolysis products were identified by HPLC-MS and GC–MS, and quantified by HPLC-UV-RID and IC. The highest carbon mineralization efficiency, corresponding to 30% of the oxidized AMX, was found for Pt/CNT modified electrode in carbonate buffer medium. Regarding to the AMX conversion, the results show that the effect of pH is higher than that of the electrode material. Principal component analysis allowed to determine the experimental parameters vs. product distribution relationship and to elucidate the oxidation pathways for the studied electrodes. The results show that the hydroxylation of the aromatic ring and the nitrogen atom play an important role on the efficient degradation of AMX.
Ferreira, Marta,Kuzniarska-Biernacka, Iwona,Fonseca, António M.,Neves, Isabel C.,Soares, Olívia S.G.P.,Pereira, Manuel F.R.,Figueiredo, José L.,Parpot, Pier
p. 322 - 331
(2019/07/10)

Cold-induced aldimine bond cleavage by Tris in: Bacillus subtilis alanine racemase
Pyridoxal 5′-phosphate (PLP) is a versatile cofactor involved in a large variety of enzymatic processes. Most of PLP-catalysed reactions, such as those of alanine racemases (AlaRs), present a common resting state in which the PLP is covalently bound to an active-site lysine to form an internal aldimine. The crystal structure of BsAlaR grown in the presence of Tris lacks this covalent linkage and the PLP cofactor appears deformylated. However, loss of activity in a Tris buffer only occurred after the solution was frozen prior to carrying out the enzymatic assay. This evidence strongly suggests that Tris can access the active site at subzero temperatures and behave as an alternate racemase substrate leading to mechanism-based enzyme inactivation, a hypothesis that is supported by additional X-ray structures and theoretical results from QM/MM calculations. Taken together, our findings highlight a possibly underappreciated role for a common buffer component widely used in biochemical and biophysical experiments.
Bernardo-García, Noelia,Sánchez-Murcia, Pedro A.,Espaillat, Akbar,Martínez-Caballero, Siseth,Cava, Felipe,Hermoso, Juan A.,Gago, Federico
p. 4350 - 4358
(2019/05/10)

Electrochemical synthesis of enaminones: Via a decarboxylative coupling reaction
An environmentally benign and efficient electrochemical synthesis of enaminones via a decarboxylative coupling reaction of α-keto acids using n-Bu4NI as a redox catalyst and electrolyte under constant current electrolysis in an undivided cell is reported. A broad vinyl azide substrate scope and high functional group tolerance are observed. A gram-scale reaction further demonstrates the practicability of the protocol. The results of cyclic voltammetry and control experiments indicate that I2 is likely the active species to initiate the oxidative decarboxylation via an acyl hypoiodite intermediate.
Kong, Xianqiang,Liu, Yulong,Lin, Long,Chen, Qianjin,Xu, Bo
supporting information
p. 3796 - 3801
(2019/07/31)

Synthesis of bio-based methacrylic acid from biomass-derived itaconic acid over barium hexa-aluminate catalyst by selective decarboxylation reaction
An environmentally-benign, efficient and inexpensive high-surface-area barium hexa-aluminate (BaAl12O19, BHA) was developed as a catalyst for the decarboxylation of the biomass-derived itaconic acid (IA) to bio-based methacrylic acid (MAA). A maximal 50% final yield of MAA with a high product selectivity was obtained under relatively mild synthesis reaction conditions (250 °C; 20 bar N2). The reported selective MAA production was elevated, operating process characteristics were significantly less harsh, and no depleting critical raw materials were utilized when paralleled to the procedures with alkaline mineral bases, noble metal-containing heterogeneous catalysis systems and unrenewable feed resources (e.g. isobutene), applied previously. It was found that the doping of palladium on BHA support (Pd@BHA) did not improve MAA productivity. The effect of the time (25–300 min), temperature (175–275 °C), pressure (10–40 bar), reacting substrate concentration (0.10–0.19 mol L–1), metallic oxide mass (0.5–3.0 g) and type on IA conversion, MAA content MAA content and rates was determined, examining also recyclability. BHA catalyst was characterized with various structural techniques, such as energy-dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD), CO2 temperature-programmed desorption (TPD), scanning electron microscopy (SEM) and N2 physisorption.
Bohre, Ashish,Novak, Uro?,Grilc, Miha,Likozar, Bla?
(2019/07/31)

Purification and enzymatic characterization of trans-o-hydroxybenzylidenepyruvate hydratase-aldolase from Rhodococcus opacus and enzymatic formation of α, β-unsaturated ketones
Trans-o-hydroxybenzylidenepyruvate (tHBPA) hydratase-aldolase (RnoE) catalyzes the conversion of tHBPA to 2-hydroxybenzaldehyde and pyruvate. We purified RnoE from Rhodococcus opacus and characterized its enzymatic properties. It exhibited maximum enzyme activity at 60°C and catalyzed the reverse reaction, converting various aromatic benzaldehydes and pyruvate to benzylidenepyruvate, indicating that this enzyme can be adapted for the enzymatic synthesis of α, β-unsaturated ketones.
Suzuki, Toshihiro,Takizawa, Noboru
p. 1884 - 1888
(2019/09/18)

DEHYDRATION AND CRACKING OF ALPHA-, BETA-DIHYDROXY CARBONYL COMPOUNDS TO LACTIC ACID AND OTHER PRODUCTS
Processes are disclosed for the synthesis of a cracked product from a starting substrate having a carbonyl functional group (C=O), with hydroxy-substituted carbon atoms at alpha and beta positions, relative to the carbonyl functional group. In one embodiment, an alpha-, beta-dihydroxy carboxylic acid or carboxylate is dehydrated to form a dicarbonyl intermediate by transformation of the alpha-hydroxy group to a second carbonyl group and removal of the beta-hydroxy group. The dicarbonyl intermediate is cracked to form the cracked product in which the first and second carbonyl groups are preserved. Either or both of (i) the cracked product and (ii) a second cracked product generated from cleavage of a carbon-carbon bond of the dicarbonyl intermediate, may be hydrogenated to form additional products.
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Paragraph 49-50

(2019/11/04)

The pseudoalteromonas luteoviolacea L-amino acid oxidase with antimicrobial activity is a flavoenzyme
The marine environment is a rich source of antimicrobial compounds with promising pharmaceutical and biotechnological applications. The Pseudoalteromonas genus harbors one of the highest proportions of bacterial species producing antimicrobial molecules. For decades, the presence of proteins with L-amino acid oxidase (LAAO) and antimicrobial activity in Pseudoalteromonas luteoviolacea has been known. Here, we present for the first time the identification, cloning, characterization and phylogenetic analysis of Pl-LAAO, the enzyme responsible for both LAAO and antimicrobial activity in P. luteoviolacea strain CPMOR-2. Pl-LAAO is a flavoprotein of a broad substrate range, in which the hydrogen peroxide generated in the LAAO reaction is responsible for the antimicrobial activity. So far, no protein with a sequence similarity to Pl-LAAO has been cloned or characterized, with this being the first report on a flavin adenine dinucleotide (FAD)-containing LAAO with antimicrobial activity from a marine microorganism. Our results revealed that 20.4% of the sequenced Pseudoalteromonas strains (specifically, 66.6% of P. luteoviolacea strains) contain Pl-laao similar genes, which constitutes a well-defined phylogenetic group. In summary, this work provides insights into the biological significance of antimicrobial LAAOs in the Pseudoalteromonas genus and shows an effective approach for the detection of novel LAAOs, whose study may be useful for biotechnological applications.
Andreo-Vidal, Andrés,Sanchez-Amat, Antonio,Campillo-Brocal, Jonatan C.
(2019/01/03)

One-Pot Preparation of d-Amino Acids Through Biocatalytic Deracemization Using Alanine Dehydrogenase and Ω-Transaminase
d-Amino acids are pharmaceutically important building blocks, leading to a great deal of research efforts to develop cost-effective synthetic methods. Preparation of d-amino acids by deracemization has been conceptually attractive owing to facile synthesis of racemic amino acids by Strecker synthesis. Here, we demonstrated biocatalytic deracemization of aliphatic amino acids into d-enantiomers by running cascade reactions; (1) stereoinversion of l-amino acid to a d-form by amino acid dehydrogenase and ω-transaminase and (2) regeneration of NAD+ by NADH oxidase. Under the cascade reaction conditions containing 100?mM isopropylamine and 1?mM NAD+, complete deracemization of 100?mM dl-alanine was achieved after 24?h with 95% reaction yield of d-alanine (> 99% eeD, 52% isolation yield). Graphical Abstract: [Figure not available: see fulltext.].
Han, Sang-Woo,Shin, Jong-Shik
p. 3678 - 3684
(2018/10/20)

Structural and biochemical studies on the role of active site Thr166 and Asp236 in the catalytic function of D-Serine deaminase from Salmonella typhimurium
D-Serine deaminase (DSD) degrades D-Ser to pyruvate and ammonia. Uropathogenic bacteria survive in the toxic D-Ser containing mammalian urine because of DSD activity. The crystal structure of the apo form of Salmonella typhimurium DSD (StDSD) has been reported earlier. In the present work, we have investigated the role of two active site residues, Thr166 and Asp236 by site directed mutagenesis (T166A and D236L). The enzyme activity is lost upon mutation of these residues. The 2.7 ? resolution crystal structure of T166A DSD with bound PLP reported here represents the first structure of the holo form of StDSD. PLP binding induces small changes in the relative dispositions of the minor and major domains of the protein and this inter-domain movement becomes substantial upon interaction with the substrate. The conformational changes bring Thr166 to a position at the active site favorable for the degradation of D-Ser. Examination of the different forms of the enzyme and comparison with structures of homologous enzymes suggests that Thr166 is the most probable base abstracting proton from the Cα atom of the substrate and Asp236 is crucial for binding of the cofactor.
Deka, Geeta,Bharath, Sakshibeedu R.,Savithri, Handanhal Subbarao,Murthy, Mathur Ramabhadrashastry Narasimha
p. 40 - 45
(2018/09/14)

Method for preparing pyruvic acid through catalytic oxidation of lactic acid in aqueous phase
The invention discloses a method for preparing pyruvic acid through catalytic oxidation of lactic acid in an aqueous phase. The method comprises the steps of: adopting lactic acid as a raw material, oxygen or air as an oxidant and supported nano magnesium oxide as a catalyst, performing a catalytic oxidation reaction to prepare pyruvic acid. The catalytic reaction can be carried out under the condition of normal pressure, no organic solvents are required, the product yield is high, and the catalyst can be recycled and reused.
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Paragraph 0027-0035

(2018/11/22)

Green synthesis process for pyruvic acid
The invention provides a green synthesis process for pyruvic acid. A reaction raw material which is lactic acid can be directly converted from biomass, oxygen or air is used as an oxidizing agent, andis green and safe, reaction conditions are mild, a reaction process is efficient and clean, and thus, the green synthesis process for pyruvic acid is a route for preparing pyruvic acid as an important chemical by using a biomass-based platform compound, and has important application prospect.
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Paragraph 0023; 0026; 0028; 0030

(2018/05/16)

Domino Synthesis of α,β-Unsaturated γ-Lactams by Stereoselective Amination of α-Tertiary Allylic Alcohols
Tertiary allylic alcohols equipped with a carboxyl group can be smoothly aminated under ambient conditions by a conceptually new and stereoselective protocol under palladium catalysis. The in situ formed Z-configured γ-amino acid cyclizes to afford an α,β-unsaturated γ-lactam, releasing water as the only byproduct. This practical catalytic transformation highlights the use of a carboxyl group acting as an activating and stereodirecting functional group to provide a wide series of pharma-relevant building blocks. Various control reactions support the crucial role of the carboxyl group in the substrate to mediate these transformations.
Xie, Jianing,Xue, Sijing,Escudero-Adán, Eduardo C.,Kleij, Arjan W.
supporting information
p. 16727 - 16731
(2018/11/23)

Highly Efficient Oxidation of Ethyl Lactate to Ethyl Pyruvate Catalyzed by TS-1 under Mild Conditions
Highly efficient oxidation of ethyl lactate (ELA) to ethyl pyruvate (EP) was realized over TS-1 in the presence of aqueous H2O2 (30 wt %) at low temperature without other solvent. A 100% ELA conversion and 97.8% EP yield were obtained at 50 °C after 9 h. The conversion rate of ELA is sensitive to the reaction temperature. High reaction temperature (70 °C) leads to an increase in conversion rate of ELA but causes the fast hydrolysis and decarboxylation of EP to form byproducts of acetic acid and CO2. On the basis of the characterization (pyridine-FTIR and UV-vis) and reaction results, active species of Ti(OOH) were proven. In addition, a nonradical mechanism for conversion of ELA to EP for this catalytic system was proposed. By kinetic analysis, the formation of Ti(OOH) is confirmed as the rate-determining step. The apparent activation energy (103.4 kJ mol-1) was also obtained. Furthermore, TS-1 was highly stable for the oxidation of ethyl lactate. There were almost no change in ELA conversion and EP yield throughout 10 reaction runs.
Lu, Tianliang,Zou, Junpeng,Zhan, Yuzhong,Yang, Xiaomei,Wen, Yiqiang,Wang, Xiangyu,Zhou, Lipeng,Xu, Jie
p. 1287 - 1296
(2018/02/14)

METHOD FOR THE PRODUCTION OF METHYLSUCCINIC ACID AND THE ANHYDRIDE THEREOF FROM CITRIC ACID
A process for the preparation of methylsuccinic acid in any form, including its salts, its mono- and diester derivatives and the anhydride thereof, which comprises reacting citric acid or a derivative thereof in decarboxylation conditions, said process comprising (i) reacting citric acid or mono- and diester derivatives thereof in a non- aqueous solvent, specifically excluding alcohols, on a metallic catalyst at a temperature between 50 to 400°C and under a partial hydrogen pressure from 0.1 to 50 bar or (ii) reacting citric acid or any salt thereof or mono-, di- and triester derivatives thereof on a metallic catalyst in solvents comprising at least 5% water, at a temperature of from 50 to 400°C under a hydrogen partial pressure from 0.1 to 400 bar
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Page/Page column 15

(2018/04/21)

Silica Metal Oxide Vesicles Catalyze Comprehensive Prebiotic Chemistry
It has recently been demonstrated that mineral self-assembled structures catalyzing prebiotic chemical reactions may form in natural waters derived from serpentinization, a geological process widespread in the early stages of Earth-like planets. We have s
Mattia Bizzarri, Bruno,Botta, Lorenzo,Pérez-Valverde, Maritza Iveth,Saladino, Raffaele,Di Mauro, Ernesto,García-Ruiz, Juan Manuel
p. 8126 - 8132
(2018/05/29)

Stereoselective synthesis of γ-hydroxy-α-amino acids through aldolase-transaminase recycling cascades
Efficient bi-enzymatic cascades combining aldolases and α-transaminases were designed for the synthesis of γ-hydroxy-α-amino acids. These recycling cascades provide high stereoselectivity, atom economy, and an equilibrium shift of the transamination. l-syn or anti-4-hydroxyglutamic acid and d-anti-4,5-dihydroxynorvaline were thus prepared in 83-95% yield in one step from simple substrates.
Guérard-Hélaine, Christine,Heuson, Egon,Ndiaye, Moussa,Gourbeyre, Léa,Lemaire, Marielle,Hélaine, Virgil,Charmantray, Franck,Petit, Jean-Louis,Salanoubat, Marcel,De Berardinis, Véronique,Gefflaut, Thierry
supporting information
p. 5465 - 5468
(2017/07/06)

One-Pot Production of Lactic Acid from Acetol over Dealuminated Sn-Beta Supported Gold Catalyst
Staged biomass pyrolysis or condensation of the pyrolysis vapor generates less complex and concentrated liquid product streams, which provide a very promising route to produce value-added chemicals. Acetol is one of the major light oxygenates in fractionated bio-oil. Here we report an efficient one-pot conversion of acetol to lactic acid, a key platform chemical and an important monomer of biodegradable polymer, in aqueous phase over a bifunctional dealuminated Sn-Beta supported gold catalyst. Under relatively mild conditions (393 K, 1.9 MPa N2 + 0.1 MPa O2), 93.4% acetol conversion and 73.2% selectivity toward lactic acid were achieved. On the basis of measured rate constants, the reaction pathway likely proceeds via kinetically relevant oxidation of acetol to form pyruvaldehyde, followed by hydration and 1,2-hydride shift (internal Meerwein-Ponndorf-Verley reduction and Oppenauer oxidation) on Sn-Lewis sites to produce lactic acid.
Wan, Yan,Zhuang, Mengqi,Chen, Shaopeng,Hu, Wenda,Sun, Jie,Lin, Jingdong,Wan, Shaolong,Wang, Yong
p. 6038 - 6047
(2017/09/15)

A process for the preparation method of the pyruvic acid
The present invention relates to a pyruvic acid preparation method, specifically to a method for using a molybdenum-vanadium-niobium composite metal oxide catalyst to efficiently catalyze tartaric acid to generate pyruvic acid. According to the method, a molybdenum-vanadium-niobium composite metal oxide is adopted as a catalyst, reacting is performed at a temperature of 160-210 DEG C under an oxidizing atmosphere under a negative pressure condition in the presence of a high boiling solvent, and a raw material tartaric acid is subjected to dewatering decarboxylation through catalysis to generate the pyruvic acid, wherein the reaction time is 0.5-3 h, and the catalyst use amount accounts for 5-50% of the use amount of the raw materials. According to the present invention, the catalyst is the heterogeneous catalyst, the catalyst activity is high, the product is easily separated from the catalyst, the catalyst can be recycled, the reaction temperature is low, the process operation is simple, and the catalyst provides high selectivity for pyruvic acid.
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Paragraph 0025

(2017/06/29)

Bio-inspired enantioselective full transamination using readily available cyclodextrin
The mimics of vitamin B6-dependent enzymes that catalyzed an enantioselective full transamination in the pure aqueous phase have been realized for the first time through the establishment of a new “pyridoxal 5′-phosphate (PLP) catalyzed non-covalent cyclodextrin (CD)-keto acid inclusion complexes” system, and various optically active amino acids have been obtained.
Zhang, Shiqi,Li, Guangxun,Liu, Hongxin,Wang, Yingwei,Cao, Yuan,Zhao, Gang,Tang, Zhuo
p. 4203 - 4208
(2017/02/05)

α-Keto Acids as Acylating Agents in the Synthesis of 2-Substituted Benzothiazoles and Benzoselenazoles
Herein, we report the first decarboxylative oxidation of α-keto acids that is promoted by sodium metabisulfite (Na2S2O5) to obtain 2-substituted benzothiazoles and benzoselenazoles. Diaryl disulfides and diselenides were used as chalcogen sources, and the desired products were obtained in moderate to excellent yields. This protocol does not require an inert gas, transition metals, or harsh reaction conditions, and CO2 is released as an environmentally benign coproduct. The presence of Na2S2O5 was essential to guarantee that the reaction reached completion and afforded maximum product yields.
Lima, David B.,Penteado, Filipe,Vieira, Marcelo M.,Alves, Diego,Perin, Gelson,Santi, Claudio,Lenard?o, Eder J.
supporting information
p. 3830 - 3836
(2017/07/22)

Inter- and intramolecular aldol reactions promiscuously catalyzed by a proline-based tautomerase
The enzyme 4-oxalocrotonate tautomerase (4-OT), which in nature catalyzes a tautomerization step as part of a catabolic pathway for aromatic hydrocarbons, was found to promiscuously catalyze different types of aldol reactions. These include the self-condensation of propanal, the cross-coupling of propanal and benzaldehyde, the cross-coupling of propanal and pyruvate, and the intramolecular cyclizations of hexanedial and heptanedial. Mutation of the catalytic amino-terminal proline (P1A) greatly reduces 4-OT's aldolase activities, whereas mutation of another active site residue (F50A) strongly enhances 4-OT's aldolase activities, indicating that aldolization is an active site process. This catalytic promiscuity of 4-OT could be exploited as starting point to create tailor-made, artificial aldolases for challenging self- and cross-aldolizations.
Rahimi, Mehran,Geertsema, Edzard M.,Miao, Yufeng,Van Der Meer, Jan-Ytzen,Van Den Bosch, Thea,De Haan, Pim,Zandvoort, Ellen,Poelarends, Gerrit J.
supporting information
p. 2809 - 2816
(2017/04/03)

One-step synthesis of pyruvic acid from glycerol oxidation over Pb promoted Pt/activated carbon catalysts
One-step production of pyruvic acid through selective oxidation of glycerol was investigated using lead promoted platinum/activated carbon (Pb-Pt/AC) catalysts under mild conditions. The results of N2 physisorption, X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy revealed that the alloy phases of PtPb and PtxPb were favorable for pyruvic acid production from glycerol oxidation, whereas the Pb3(CO3)2(OH)2 and surface Pb0 species inhibited the glycerol conversion. The loading of Pb and the catalyst preparation method (including impregnation and deposition precipitation) affected the formation of different metal species. Pyruvic acid was obtained at a yield of 18.4% on a 5.0 wt% Pb-5.0 wt% Pt/AC catalyst prepared by co-deposition precipitation method and 500 °C argon treatment.
Zhang, Chen,Wang, Tao,Ding, Yunjie
p. 928 - 937
(2017/05/22)

Efficient Enzymatic Preparation of13N-Labelled Amino Acids: Towards Multipurpose Synthetic Systems
Nitrogen-13 can be efficiently produced in biomedical cyclotrons in different chemical forms, and its stable isotopes are present in the majority of biologically active molecules. Hence, it may constitute a convenient alternative to Fluorine-18 and Carbon-11 for the preparation of positron-emitter-labelled radiotracers; however, its short half-life demands for the development of simple, fast, and efficient synthetic processes. Herein, we report the one-pot, enzymatic and non-carrier-added synthesis of the13N-labelled amino acids l-[13N]alanine, [13N]glycine, and l-[13N]serine by using l-alanine dehydrogenase from Bacillus subtilis, an enzyme that catalyses the reductive amination of α-keto acids by using nicotinamide adenine dinucleotide (NADH) as the redox cofactor and ammonia as the amine source. The integration of both l-alanine dehydrogenase and formate dehydrogenase from Candida boidinii in the same reaction vessel to facilitate the in situ regeneration of NADH during the radiochemical synthesis of the amino acids allowed a 50-fold decrease in the concentration of the cofactor without compromising reaction yields. After optimization of the experimental conditions, radiochemical yields were sufficient to carry out in vivo imaging studies in small rodents.
da Silva, Eunice S.,Gómez-Vallejo, Vanessa,Baz, Zuri?e,Llop, Jordi,López-Gallego, Fernando
p. 13619 - 13626
(2016/09/13)

Transporter engineering and enzyme evolution for pyruvate production from d/l-alanine with a whole-cell biocatalyst expressing l-amino acid deaminase from Proteus mirabilis
Pyruvate is an essential metabolite in the central metabolism of microbes, and it has been widely used in the food, pharmaceutical, and agrochemical industries. Both chemical and biological processes have been used for industrial pyruvate production. In this study, one-step pyruvate production from d/l-alanine with a whole-cell E. coli biocatalyst expressing l-amino acid deaminase (pm1) from Proteus mirabilis was investigated. Alanine uptake transporters (cycA, amaP) and a pyruvate uptake transporter (lldP) were knocked out to prevent substrate and product utilization by the biocatalyst. The pyruvate production titer from d/l-alanine increased from 1.14 g L-1 under control conditions to 5.38 g L-1 with the mutant whole-cell biocatalyst. Directed evolution was used to engineer pm1 and improve the catalytic activity with d/l-alanine. Three rounds of error-prone polymerase chain reaction generated the mutant pm1ep3, which showed improved affinity (6.76 mM for l-alanine) and catalytic efficiency (0.085 s-1 mM-1 and 0.027 s-1 mM-1 for l- and d-alanine, respectively). The final pyruvate titer was increased to 14.57 g L-1 and the conversion ratio was increased to 29.14% by using the engineered whole-cell biocatalyst containing the evolved pm1ep3.
Hossain, Gazi Sakir,Shin, Hyun-Dong,Li, Jianghua,Du, Guocheng,Chen, Jian,Liu, Long
p. 82676 - 82684
(2016/11/15)

ENZYMATIC METHODS FOR ISOBUTANOL PRODUCTION
The present invention relates to a process of producing isobutanol, including: mixing water, lactate, an enzyme mixture including at least one enzyme, at least one cofactor, and at least one coenzyme, to prepare a reaction mixture; allowing catalytic conversions of lactate in the reaction mixture for a sufficient amount of time to produce isobutanol; and separating the isobutanol from a reactant obtained by the catalytic conversions, in which the conversion of lactate into isobutanol is in association with a NAD+/NADH and/or NADP+/NADPH regenerating system.
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Paragraph 00133-00137

(2016/07/05)

Enzymatic Resolution by a d-Lactate Oxidase Catalyzed Reaction for (S)-2-Hydroxycarboxylic Acids
Oxidase-catalyzed kinetic resolution is important for the production of enantiopure 2-hydroxycarboxylic acids (2-HAs), which are versatile building blocks for the synthesis of many significant compounds. However, in contrast to that of (R)-2-HAs, the production of (S)-2-HA is challenging because of the lack of related oxidases. Herein, suitable enzymes were screened systematically through the analysis of numerous putative d-lactate oxidase sequences and identification of several required properties. Finally, a d-lactate oxidase from Gluconobacter oxydans 621H with advantageous characteristics, such as good solubility, broad substrate spectrum, and high stereoselectivity, was selected to resolve 2-HAs into (S)-2-HAs. A variety of (S)-2-HAs was produced successfully using this d-lactate oxidase with excellent enantiomeric excess values (>99 %). The presented screening criteria and approach for target biocatalysis suggested a guideline for the production of optically active chemicals such as (S)-2-HAs.
Sheng, Binbin,Xu, Jing,Ge, Yongsheng,Zhang, Shuo,Wang, Danqi,Gao, Chao,Ma, Cuiqing,Xu, Ping
p. 2630 - 2633
(2016/08/30)

A highly oxidized diterpine compound and its preparation method and medical use (by machine translation)
The invention discloses a highly-oxidized diterpenoid compound and a preparation method and medical application thereof and belongs to the technical field of medicines. The compound is disclosed for the first time, is a diterpenoid compound with a novel structure and can be prepared from dried flower buds of common coltsfoot flowers through extraction, separation and purification. An in-vitro test proves that the compound has the protection effect on vascular endothelial cells suffering from H2O2 oxidative damage, further has free radical scavenging and reactive oxygen resisting characteristics and can be used for developing vascular protection drugs.
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Paragraph 0050

(2017/05/18)

A Global Scale Scenario for Prebiotic Chemistry: Silica-Based Self-Assembled Mineral Structures and Formamide
The pathway from simple abiotically made organic compounds to the molecular bricks of life, as we know it, is unknown. The most efficient geological abiotic route to organic compounds results from the aqueous dissolution of olivine, a reaction known as serpentinization (Sleep, N.H., et al. (2004) Proc. Natl. Acad. Sci. USA 101, 12818-12822). In addition to molecular hydrogen and a reducing environment, serpentinization reactions lead to high-pH alkaline brines that can become easily enriched in silica. Under these chemical conditions, the formation of self-assembled nanocrystalline mineral composites, namely silica/carbonate biomorphs and metal silicate hydrate (MSH) tubular membranes (silica gardens), is unavoidable (Kellermeier, M., et al. In Methods in Enzymology, Research Methods in Biomineralization Science (De Yoreo, J., Ed.) Vol. 532, pp 225-256, Academic Press, Burlington, MA). The osmotically driven membranous structures have remarkable catalytic properties that could be operating in the reducing organic-rich chemical pot in which they form. Among one-carbon compounds, formamide (NH2CHO) has been shown to trigger the formation of complex prebiotic molecules under mineral-driven catalytic conditions (Saladino, R., et al. (2001) Biorganic & Medicinal Chemistry, 9, 1249-1253), proton irradiation (Saladino, R., et al. (2015) Proc. Natl. Acad. Sci. USA, 112, 2746-2755), and laser-induced dielectric breakdown (Ferus, M., et al. (2015) Proc Natl Acad Sci USA, 112, 657-662). Here, we show that MSH membranes are catalysts for the condensation of NH2CHO, yielding prebiotically relevant compounds, including carboxylic acids, amino acids, and nucleobases. Membranes formed by the reaction of alkaline (pH 12) sodium silicate solutions with MgSO4 and Fe2(SO4)3·9H2O show the highest efficiency, while reactions with CuCl2·2H2O, ZnCl2, FeCl2·4H2O, and MnCl2·4H2O showed lower reactivities. The collections of compounds forming inside and outside the tubular membrane are clearly specific, demonstrating that the mineral self-assembled membranes at the same time create space compartmentalization and selective catalysis of the synthesis of relevant compounds. Rather than requiring odd local conditions, the prebiotic organic chemistry scenario for the origin of life appears to be common at a universal scale and, most probably, earlier than ever thought for our planet.
Saladino, Raffaele,Botta, Giorgia,Bizzarri, Bruno Mattia,Di Mauro, Ernesto,Garcia Ruiz, Juan Manuel
p. 2806 - 2811
(2016/06/01)

Hydrothermal conversion of glucose into lactic acid with sodium silicate as a base catalyst
In this paper, the hydrothermal conversion of glucose to lactic acid (LA) using sodium silicate (Na2SiO3) as a mild base catalyst was investigated. The results showed that Na2SiO3 was effective catalyst for the conversion of glucose. The highest LA yield of about 30% was obtained from glucose with a lower concentration of Na2SiO3 at 300 °C for 60 s. It was also found that the use of Na2SiO3 led to a much less corrosion and a higher LA yield than that with NaOH at the same pH value. This process provides an environmentally friendly and highly effective method toward the synthesis of useful LA from glucose.
Duo, Jia,Zhang, Zhengshuai,Yao, Guodong,Huo, Zhibao,Jin, Fangming
p. 112 - 116
(2016/02/03)

Catalytic wet air oxidation of m-cresol over a surface-modified sewage sludge-derived carbonaceous catalyst
Sewage sludge-derived carbonaceous materials (SW) treated with different kinds of acids were used as catalysts for catalytic wet air oxidation (CWAO) of m-cresol. The SW catalysts were characterized by XRF, XRD, FTIR, XPS and TPD-MS. The results showed that SW treated with HNO3 (HNO3-SW) exhibited the best catalytic activity. When the initial concentration of m-cresol was 5000 mg L-1, the conversion of m-cresol reached 99.0% with HNO3-SW after 90 min at 160 °C and 0.66 MPa oxygen. Continuous experiments were carried out for 8 d to investigate the durability and catalytic performance of HNO3-SW in CWAO reaction. Some correlation was observed between the conversion of m-cresol and the content of carboxyl groups, indicating that the carboxyl group might play a key role in determining the catalytic activity of SW catalysts in CWAO reaction. Based on the intermediate products identified by GC-MS, HPLC-MS, IC and HRMS analyses, the oxidation pathways of m-cresol in CWAO were proposed.
Yu, Yang,Wei, Huangzhao,Yu, Li,Gu, Bin,Li, Xianru,Rong, Xin,Zhao, Ying,Chen, Lili,Sun, Chenglin
p. 1085 - 1093
(2016/02/27)

Validation of the metabolic pathway of the alginate-derived monomer in Saccharophagus degradans 2-40T by gas chromatography–mass spectrometry
Marine macroalgae are potential resources for the sustainable production of biofuels and bio-based chemicals. Alginate, a major component of brown macroalgae, consists of two uronate monomers, which are further non-enzymatically converted to 4-deoxy-L-erythro-5-hexoseulose uronate (DEH). In several marine bacteria, DEH is known to be metabolized via three enzymatic steps, consisting of DEH reductase, 2-keto-3-deoxy-D-gluconate (KDG) kinase, and 2-keto-3-deoxy-phosphogluconate (KDPG) aldolase, which yields two glycolytic intermediates: D-glyceraldehyde-3-phosphate and pyruvate. However, such functions of these enzymes for the DEH pathway have rarely been experimentally validated. In the present study, the DEH metabolic pathway was investigated in Saccharophagus degradans 2-40T, a marine bacterium that utilizes alginate. Through in vitro tests assisted by gas chromatography/mass spectrometry and gas chromatography/time-of-flight mass spectrometry, the purified enzymes were functionally confirmed and annotated as dehR, kdgK, and kdpgA, respectively. In conclusion, we report the in vitro validation of the metabolic pathway of DEH monomerized from alginate.
Kim, Do Hyoung,Wang, Damao,Yun, Eun Ju,Kim, Sooah,Kim, Soo Rin,Kim, Kyoung Heon
p. 1374 - 1379
(2016/10/03)

Kinetic and solvent isotope effects on biotransformation of aromatic amino acids and their derivatives
Aromatic amino acids such as l-phenylalanine, l-tryptophan, 3′,4′-dihydroxy-l-phenylalanine (l-DOPA), and their derivatives 3′,4′-dihydroxyphenylacelaldehyde (DOPAL) and 3′,4′-dihydroxyphenylethanol (DOPET), play an essential role in human metabolic processes. Incorrect or slow biotransformation of these compounds leads to some metabolic dysfunctions and in some cases to some neurodegenerative diseases. Therefore, studies of the biotransformation mechanisms of these metabolites draw biochemists' and medical researchers' attention. This study investigates the mechanisms of biotransformation of the aforementioned compounds using kinetic (KIE) and solvent (SIE) isotope effect methods. The overview presents the results and the numerical values of KIE and SIE methods, obtained in the study of biotransformation of l-phenylalanine, 5′-chloro-l-tryptophan, and l-DOPA, catalyzed by the enzymes from the lyases group (phenylalanine ammonia lyase, tryptophan indole-lyase, and tyrosine decarboxylase). Deuterium KIE was also determined during the deamination of 2′-chloro-l-phenylalanine in the presence of the enzyme l-phenylalanine dehydrogenase, as well as in the conversion of DOPAL into DOPET catalyzed by the enzyme alcohol dehydrogenase. The values of KIE and SIE have been determined using a noncompetitive spectrophotometric and a competitive (combined with internal radioactivity standard) radiometric methods.
Kańska, Marianna,Jemielity, Jacek,Paj?k, Ma?gorzata,Pa?ka, Katarzyna,Podsadni, Katarzyna,Winnicka, El?bieta
p. 627 - 634
(2016/12/26)

An artificial enzymatic reaction cascade for a cell-free bio-system based on glycerol
Conversion of glycerol into high-value products is of significant importance for sustainability in the biofuel industry. In this study, pyruvic acid, a central intermediate needed for the production of versatile biomolecules, was produced from glycerol without the addition of any cofactors by the cell-free bio-system composed of alditol oxidase, dihydroxy acid dehydratase, and catalase. (3R)-Acetoin was then produced at 85.5% of the theoretical yield from glycerol by α-acetolactate synthase and α-acetolactate decarboxylase. Since other biomolecules can also be produced from pyruvic acid, the cell-free bio-system might serve as a versatile bio-production platform, and support the viability of the biofuel economy. This journal is
Gao, Chao,Li, Zhong,Zhang, Lijie,Wang, Chao,Li, Kun,Ma, Cuiqing,Xu, Ping
supporting information
p. 804 - 807
(2015/03/04)

Au/Pt/TiO2 catalysts prepared by redox method for the chemoselective 1,2-propanediol oxidation to lactic acid and an NMR spectroscopy approach for analyzing the product mixture
1,2-propanediol obtained from the waste glycerol is the most prominent substrate to produce lactic acid (LA) through the sustainable green catalytic oxidative route. We showed that bimetallic Au/Pt/TiO2 catalysts that could be easily prepared by the redox reaction with preadsorbed hydrogen possessed a high activity in the formation of lactic acid from 1,2-propanediol through selective primary hydroxyl group oxidation by an oxygen-air mixture or an air. The most efficient catalyst with the highest TON value was the sample with the lowest Au content. Even the addition of 0.025 wt.% of gold to the 1%Pt/TiO2 catalyst by the redox method resulted in the enhanced 1,2-propanediol conversion up to 96% with the 91% selectivity to LA. The high oxidation activity of the Au/Pt/TiO2 catalysts was ascribed to the strong interaction between the two metals in Au/Pt bimetallic particles and between the bimetallic particles and the support, which was proved by X-ray photoelectron spectroscopy (XPS) analysis, Fourier transform infrared spectroscopy of adsorbed CO (DRIFTS) technique, and temperature programmed reduction method (TPR-H2). The reaction products were identified and analyzed with the use of 1D and 2D nuclear magnetic resonance spectroscopy (NMR) methods, which also allowed suggesting a plausible up-to-date scheme of 1,2-propanediol catalytic oxidation.
Redina, Elena,Greish, Alexander,Novikov, Roman,Strelkova, Anastasiya,Kirichenko, Olga,Tkachenko, Olga,Kapustin, Gennady,Sinev, Ilya,Kustov, Leonid
p. 170 - 183
(2015/05/05)