- Mechanism of cysteine-dependent inactivation of aspartate/glutamate/ cysteine sulfinic acid α-decarboxylases
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Animal aspartate decarboxylase (ADC), glutamate decarboxylase (GDC) and cysteine sulfinic acid decarboxylase (CSADC) catalyze the decarboxylation of aspartate, glutamate and cysteine sulfinic acid to β-alanine, γ-aminobutyric acid and hypotaurine, respectively. Each enzymatic product has been implicated in different physiological functions. These decarboxylases use pyridoxal 5-phosphate (PLP) as cofactor and share high sequence homology. Analysis of the activity of ADC in the presence of different amino determined that beta-alanine production from aspartate was diminished in the presence of cysteine. Comparative analysis established that cysteine also inhibited GDC and CSADC in a concentration-dependent manner. Spectral comparisons of free PLP and cysteine, together with ADC and cysteine, result in comparable spectral shifts. Such spectral shifts indicate that cysteine is able to enter the active site of the enzyme, interact with the PLP-lysine internal aldimine, form a cysteine-PLP aldimine and undergo intramolecular nucleophilic cyclization through its sulfhydryl group, leading to irreversible ADC inactivation. Cysteine is the building block for protein synthesis and a precursor of cysteine sulfinic acid that is the substrate of CSADC and therefore is present in many cells, but the presence of cysteine (at comparable concentrations to their natural substrates) apparently could severely inhibit ADC, CSADC and GDC activity. This raises an essential question as to how animal species prevent these enzymes from cysteine-mediated inactivation. Disorders of cysteine metabolism have been implicated in several neurodegenerative diseases. The results of our study should promote research in terms of mechanism by which animals maintain their cysteine homeostasis and possible relationship of cysteine-mediated GDC and CSADC inhibition in neurodegenerative disease development.
- Liu, Pingyang,Torrens-Spence, Michael P.,Ding, Haizhen,Christensen, Bruce M.,Li, Jianyong
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- Photocatalytic One-Step Syntheses of Cyclic Imino Acids by Aqueous Semiconductor Suspensions
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Optically active cyclic imino acids, pipecolinic acid and proline, are readily obtained from α,ω-diamino carboxylic acids and their Nω-substituted derivatives by the photoirradiation of aqueous suspensions of TiO2 or CdS loaded with platinum oxides under Ar at room temperature.
- Ohtani, Bunsho,Tsuru, Shigeto,Nishimoto, Sei-ichi,Kagiya, Tsutomu
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- Abiotic Synthesis of Amino Acids by Proton Irradiation of a Mixture of Carbon Monoxide, Nitrogen, and Water
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We have shown that proton irradiation simulating the action of cosmic rays and solar flare particles formed proteinous and non-proteinous amino acids such as glycine, alanine, aspartic acid and β-alanine from a mixture of carbon monoxide, carbon dioxide, nitrogen and water.The yield of amino acids per unit energy was the highest obtained among various prebiotic energy sources used.This result suggests the possibility of the formation of amino acids mildly reduced primitive atmospheres on the earth.
- Kobayashi, Kensei,Oshima, Tairo,Yanagawa, Hiroshi
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- Mass spectrometry assay for studying kinetic properties of dipeptidases: Characterization of human and yeast dipeptidases
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Chemical modifications of substrate peptides are often necessary to monitor the hydrolysis of small bioactive peptides. We developed an electrospray ionization mass spectrometry (ESI-MS) assay for studying substrate distributions in reaction mixtures and determined steady-state kinetic parameters, the Michaelis-Menten constant (Km), and catalytic turnover rate (V max/[E]t) for three metallodipeptidases: two carnosinases (CN1 and CN2) from human and Dug1p from yeast. The turnover rate (V max/[E]t) of CN1 and CN2 determined at pH 8.0 (112.3 and 19.5 s-1, respectively) suggested that CN1 is approximately 6-fold more efficient. The turnover rate of Dug1p for Cys-Gly dipeptide at pH 8.0 was found to be slightly lower (73.8 s-1). In addition, we determined kinetic parameters of CN2 at pH 9.2 and found that the turnover rate was increased by 4-fold with no significant change in the Km. Kinetic parameters obtained by the ESI-MS method are consistent with results of a reverse-phase high-performance liquid chromatography (RP-HPLC)-based assay. Furthermore, we used tandem MS (MS/MS) analyses to characterize carnosine and measured its levels in CHO cell lines in a time-dependent manner. The ESI-MS method developed here obviates the need for substrate modification and provides a less laborious, accurate, and rapid assay for studying kinetic properties of dipeptidases in vitro as well as in vivo.
- Pandya, Vaibhav,Ekka, Mary Krishna,Dutta, Rajesh Kumar,Kumaran
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- Artificial trinuclear metallopeptidase synthesized by cross-linkage of a molecular bowl with a polystyrene derivative
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A novel methodology is reported for construction of active sites of artificial multinuclear metalloenzymes: Transfer of metal-chelating sites confined in a prebuilt cage to a polymeric backbone. Artificial active sites comprising two or three moieties of Cu(II) complex of tris(2-aminoethyl)amine (tren) were prepared by transfer of Cu(II)tren units confined in a molecular bowl (MB) to poly(chloromethylstyrene-co-divinylbenzene) (PCD). By treatment of unreacted chloro groups of the resulting PCD with methoxide and destruction of the MB moieties attached to PCD with acid followed by addition of Cu(II) ion to the exposed tren moieties, catalytic polymers with peptidase activity were obtained. The average number (β) of proximal Cu(II)tren moieties in the active site of the artificial multinuclear metallopeptidase was determined by quantifying the Cu(II) content. Several species of the artificial metallopeptidases with different β contents were prepared and examined for catalytic activity in hydrolysis of various cinnamoyl amide derivatives. The PCD-based catalytic polymers did not hydrolyze a neutral amide but effectively hydrolyzed carboxyl-containing amides (N-cinnamoyl glycine, N-cinnamoyl β-alanine, and N-cinnamoyl γ-amino butyrate). Analysis of the kinetic data revealed that the active sites comprising three Cu(II)tren units were mainly responsible for the catalytic activity. When analyzed in terms of k(cat), the catalytic activity of the PCD-based artificial peptidase was comparable to or better than the catalytic antibody with the highest peptidase activity reported to date. A mechanism is suggested for the effective cooperation among the three metal centers of the active site in hydrolysis of the carboxyl-containing amides.
- Moon, Sung-Ju,Jeon, Joong Won,Kim, Heesuk,Suh, Myunghyun Paik,Sun, Junghun
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- KINETICS OF THE FORMATION OF PANTOLACTONE FROM PANTOTHENATES AND ITS QUANTITATIVE DETERMINATION
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The conditions of hydrolysis and lactonization of the calcium and sodium salts of pantothenic and pantoic acids have been studied.The selected conditions of hydrolysis (t = 80 deg C, CHCl = 13percent) led to a 100percent yield of β-alanine and pantothenates after 60 min from the beginning of hydrolysis, while the formation of pantolactone was complete in 105 min for the calcium salt and in 75 min for the sodium salt.The hydrolysis and lactonization reactions have been performed under the conditions mentioned, and the GLC of the pantolactone formed has permitted the determination of various concentrations of calcium pantothenate.The results obtained from the GLC analysis of pantolactone indicate the possibility of a quantitative determination of salts of pantothenic and pantoic acids.The sensitivity of this method is 0.2-5 nmole.
- Moiseenok, A. G.,Slyshenkov, V. S.,Lysenkova, A. V.
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- A green-by-design bioprocess for l-carnosine production integrating enzymatic synthesis with membrane separation
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l-Carnosine (l-Car, β-alanyl-l-histidine) is a bioactive dipeptide with important physiological functions. Direct coupling of unprotected β-Ala (β-alanine) with l-His (l-histidine) mediated by an enzyme is a promising method for l-Car synthesis. In this study, a new recombinant dipeptidase (SmPepD) from Serratia marcescens with a high synthetic activity toward l-Car was identified by a genome mining approach and successfully expressed in Escherichia coli. Divalent metal ions strongly promoted the synthetic activity of SmPepD, with up to 21.7-fold increase of activity in the presence of 0.1 mM MnCl2. Higher temperature, lower pH and increasing substrate loadings facilitated the l-Car synthesis. Pilot biocatalytic syntheses of l-Car were performed comparatively in batch and continuous modes. In the continuous process, an ultra-filtration membrane reactor with a working volume of 5 L was employed for catalyst retention. The dipeptidase, SmPepD, showed excellent operational stability without a significant decrease in space-time yield after 4 days. The specific yield of l-Car achieved was 105 gCar gcatalyst-1 by the continuous process and 30.1 gCar gcatalyst-1 by the batch process. A nanofiltration membrane was used to isolate the desired product l-Car from the reaction mixture by selectively removing the excess substrates, β-Ala and l-His. As a result, the final l-Car content was effectively enriched from 2.3% to above 95%, which gave l-Car in 99% purity after ethanol precipitation with a total yield of 60.2%. The recovered substrate mixture of β-Ala and l-His can be easily reused, which will enable the economically attractive and environmentally benign production of the dipeptide l-Car.
- Yin, Dong-Ya,Pan, Jiang,Zhu, Jie,Liu, You-Yan,Xu, Jian-He
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- Fixation of Molecular Nitrogen Using Aliphatic Carboxylic Acid by Nitrogen Arc Plasma. Formation of Amino Acids
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When argon-nitrogen plasma was blown into an aqueous solution containing aliphatic carboxylic acids, formation of several amino acids and amines was identified.
- Takasaki, Michiaki,Harada, Kaoru
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- TRANSFORMATIONS OF ACRYLAMIDE AND POLYACRYLAMIDE AT HIGH PRESSURES AND LARGE SHEAR DEFORMATIONS
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Radical polymerization and nucleophilic addition of an amide group to the double bond of acrylamide take place parallel in conditions of shear deformation and high pressures (up to 8 GPa). Large shear deformations cause the formation of β-alanine as the result of reactions of hydrolysis of amide groups and peptide bonds. Keywords: pressure, shear deformation, acrylamide, polyacrylamide, radical polymerization, nucleophilic addition, hydrolysis, β-alanine.
- Chistotina, N. P.,Zharov, A. A.
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- Kinetic and spectroscopic evidence of negative cooperativity in the action of lysine 2,3-aminomutase
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Lysine 2,3-aminomutase (LAM) catalyzes the interconversion of l-lysine and l-β-lysine, a component of a number of antibiotics. The reaction requires the cofactors S-adenosyl-l-methionine (SAM), pyridoxal-5′-phosphate (PLP), and a [4Fe-4S] cluster. LAM is a founding member of the radical SAM superfamily of enzymes. LAM is highly specific for l-lysine and will not accept most other amino acids as substrates. l-Alanine and l-2-aminobutyrate at 0.2 M react as substrates for LAM at, respectively, 5 × 10-6 and 8 × 10-5 times the rate with saturating l-lysine. Saturating ethylamine accelerates the l-alanine reaction 70-fold, and saturating methylamine accelerates the l-2-aminobutyrate reaction 47-fold. The primary amines binding at the active site of LAM with l-alanine or l-2-aminobutyrate simulate l-lysine. The steady-state kinetics of the reaction of l-alanine + ethylamine displays negative cooperativity with respect to l-alanine. The second-order rate constant for production of β-alanine in the reaction of l-alanine and saturating ethylamine is 0.040 M-1 s-1, which is 2 × 10 -5 times the value of kcat/Km for the reaction of l-lysine. When l-lysine is at a concentration 1/16th of Km, the lysyl-free radical intermediate is hardly detectable by EPR; however, the addition of l-alanine at high concentration (0.2 M) enhances free radical formation, and the addition of ethylamine further enhances radical formation. These facts complement the kinetic observations and support negative cooperativity in the reaction of l-alanine as a substrate for LAM. Present results and independent evidence support negative cooperativity in the reaction of l-lysine as well.
- Ruzicka, Frank J.,Frey, Perry A.
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- Degradation of complexons derived from succinic acid under UV radiation
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The destruction of complexons derived from succinic acid under the action of UV radiation was studied. IR spectroscopy, thin-layer paper chromatography, and complexometric titration were used to determine the destruction products of these complexons. It was found that the complexons decompose under UV irradiation substantially more easily than ethylenediaminetetraacetic acid does, and the products of their decomposition can undergo a biological utilization under natural conditions. The data obtained in the study make it possible to choose, instead of ethylenediaminetetraacetic acid, ligands that will be nearly fully destructible in the light without deteriorating the ecology.
- Smirnova,Khizhnyak,Nikol’skii,Khalyapina, Ya. M.,Pakhomov
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- Cleavage of the peptide bond of β-alanyl-L-histidine (carnosine) induced by a CoIII-amine complexes: Reaction, structure and mechanism
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Cleavage of the peptide bond occurs when β-alanyl-L-histidine (carnosine) reacts with [Co(tren)Cl2] (tren = tris(2-aminoethyl) amine) to give [Co(tren)(histidine)]2- 1 and [Co(tren)(β- alanine)]2- 2. [Co(tren)(histidine)]2- 1 crystallizes in the enantiomorphic space group P212121 and 2 crystallizes in the P21/c space group. The mechanism of the cleavage reactions were studied in detail for the precursor [Co(tren)Cl2] + and [Co(trien)Cl2]+, which convert into [Co(tren)(OH)2]+/[Co(tren)(OH)(OH2)] 2+ and [Co(trien)(OH)2]+/[Co(trien)(OH)(OH 2)]2+ in water at basic pH [trien = 1,4,7,10- tetraazadecane). At a slightly basic pH, the initial coordination of the substrate (β-alanyl-L-histidine) is by the carboxylate group for the reaction with [Co(tren)Cl2]+. This is followed by a rate-limiting nucleophilic attack of the hydroxide group at the β-alanyl-L-histidine carbonyl group. In a strongly basic reaction medium substrate, binding of the metal was through carboxylate and amine terminals. On the other hand, for the reaction between [cis-β-Co(trien)Cl 2]+ and β-alanyl-L-histidine, the initial coordination of the substrate takes place via an imidazole ring nitrogen, independently, and followed by a nucleophilic attack of the hydroxide group at the β-alanyl-L-histidine carbonyl group. The circular dichroism spectrum for 1 suggests that a very small extent of racemization of the amino acid (L-histidine) takes place during the cleavage reaction between [Co(tren)Cl 2]+ and β-alanyl-L-histidine. Reaction between [cw-β-Co(trien)Cl2]+ and β-alanyl-L-histidine also causes cleavage of the peptide bond, producing a free β-alanyl molecule and a cationic fragment [cis-α-Co(trien)(histidine)]2+ 3 that crystallizes in the optically active space group P212 121. Unlike the previous case an appreciable degree of racemization of the L-histidine takes place during the reaction between [cis-β-Co(trien)Cl2]+ and β-alanyl-L-histidine. Crystals containing L-histidine and D-histidine fragments in the [cis-α-Co(trien)(histidine)]2- moiety were crystallographically documented by mounting a number of randomly selected crystals.
- Saha, Manas K.,Mukhopadhyay, Uday,Bernal, Ivan
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- FORMATION OF AMINO ACIDS FROM ALIPHATIC AMINES BY CONTACT GLOW DISCHARGE ELECTROLYSIS
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Oxidation of aliphatic amines in an aqueous solution by contact glow discharge electrolysis resulted in the formation of several amino acids, which was explained by the oxidative action of hydroxyl radical generated by the electric discharge process to the aqueous solution.
- Harada, Kaoru,Nomoto, Masayo M.,Gunji, Hiromi
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- THE FORMATION OF α- AND β-ALANINE BY THE INSERTION OF NH(1Δ) RADICALS INTO THE C-H BONDS OF PROPIONIC ACID
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The formation of α- and β-alanine in the photolysis of hydrogen azide in propionic acid was confirmed by the NMR spectra.The yield ratios, alanine/nitrogen and β/α in alanine were found to be 0.4 and 1.5, respectively, suggesting that NH(1Δ) radicals insert into the C-H bonds of propionic acid.
- Sato, Shin,Kitamura, Takashi,Tsunashima, Shigeru
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- Formation of amino acids from possible interstellar media by γ-rays and UV irradiation
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Formation of amino acids from mixtures of methanol, ammonia and water in various phases by γ-rays and UV irradiation were quantitatively verified. A wide variety of amino acids were detected in every hydrosate of the product. Each G-value (the number of formed molecules per deposit energy of 100eV) was around 10-2 order, which was independent from the phase of the starting materials and kind of the energy.
- Takano, Yoshinori,Masuda, Hitomi,Kaneko, Takeo,Kobayashi, Kensei
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- Nitrilase-catalyzed hydrolysis of 3-aminopropionitrile at high concentration with a tandem reaction strategy for shifting the reaction to β-alanine formation
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Given the importance of β-alanine, the nitrilase BjNIT3397 from Bradyrhizobium japonicum strain USDA110 was examined toward the hydrolysis of 3-aminopropionitrile. It has been found that nitrilase BjNIT3397 effectively hydrolyzed 3-aminopropionitrile with substrate concentration up to 3 M (210 g/L) at the pH 7.3 and temperature 30°C. With the increase of substrate concentration from 0.6 to 3 M, 3-aminopropanamide was formed and its percentage in the products was increased up to 33%. In order to reduce the formation of 3-aminopropanamide, aspartate ammonia-lyase and fumaric acid were added into the reaction system to consume the byproduct ammonia. As expected, the reaction was shifted toward the formation of β-alanine, resulting in the decrease of 3-aminopropanamide from 33% to 3%. Therefore, a tandem reaction strategy was developed to effectively prevent the formation of 3-aminopropanamide. This might also offer a possibility of producing β-alanine and L-aspartic acid in one process.
- Han, Chao,Yao, Peiyuan,Yuan, Jing,Duan, Yitao,Feng, Jinhui,Wang, Min,Wu, Qiaqing,Zhu, Dunming
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- FLAME-INDUCED OXIDATION OF ALIPHATIC AMINES IN AN AQUEOUS SOLUTION
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When a town gas-, a hydrogen-, and an ethylene-oxigen flame were blown against the surface of aqueous solution of aliphatic amines, the amines were effectively oxidized to afford amino acids.
- Nomoto, Shinya,Takasaki, Michiaki,Sakata, Naoko,Harada, Kaoru
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- Production of β-Alanine from Fumaric Acid Using a Dual-Enzyme Cascade
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The aim of this study was to develop an environmentally safe and efficient method for β-alanine production using a dual-enzyme cascade route with L-aspartase (AspA) from E. coli and L-aspartate-α-decarboxylase (PanD) from Corynebacterium glutamicum. Poor cooperativity in this system due to the divergent catalysis efficiencies of AspA and PanD led to an imbalance between the two reactions. To address this issue, we employed ribosome binding site regulation and gene duplication to coordinate the expression levels of AspA and PanD. Finally, we achieved β-alanine production of 80.4±1.6 g L?1 with a conversion rate of 95.3±1.6 % in a 5-L bioreactor. The dual-enzyme cascade reported herein represents a promising strategy to meet industrial requirements for large-scale β-alanine production in the future.
- Qian, Yuanyuan,Liu, Jia,Song, Wei,Chen, Xiulai,Luo, Qiuling,Liu, Liming
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- Reductive Fixation of Molecular Nitrogen by Glow Discharge against Water
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The reductive fixation of molecular nitrogen by glow discharge against water resulted in the formation of ammonia; amino compounds were also formed when the aqueous solution contained carboxylic acids.
- Harada, Kaoru,Igari, Shun-ichiro,Takasaki, Michiaki,Shimoyama, Akira
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- The Synthesis of Triterpenic Amides on the Basis of 2,3-seco-1-Cyano- 19β,28-Epoxy-18α-Oleane-3-oic Acid
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Novel 2,3-seco-triterpenic amides were prepared by the interaction of the chloride of 1-cyano-19β,28-epoxy-18α-oleane-3-oic acid with primary amines and synthetic and biogenic amino acids. A cytotoxic triterpenic conjugate with a residue of the ethyl ester of β-alanine was found among the synthesized nitrogen-containing derivatives. Treatment with this conjugate in a concentration of 100 μM resulted in the 45.5% survival of melanoma cells in the medium. Pleiades Publishing, Ltd., 2010.
- Tolmacheva,Igosheva,Grishko,Zhukova,Gerasimova
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- A study on the applicability of l-aspartate α-decarboxylase in the biobased production of nitrogen containing chemicals
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β-Alanine could serve as an intermediate in the biobased production of nitrogen containing chemicals from l-aspartic acid. Following the biorefinery concept, l-aspartic acid could become widely available from biomass waste streams via the nitrogen storage polypeptide cyanophycin. Since α-decarboxylation of l-aspartic acid is difficult to perform chemically, the applicability of Escherichia colil-aspartate α-decarboxylase (EC 4.1.1.11) (ADC) for the production of β-alanine was studied. With an increasing activity up to 90 °C and maintaining its activity upon storage for 24 hours at 60 °C, ADC showed a remarkably high thermostability. ADC has an optimum at pH 7.5 and starts to lose activity upon storage below pH 6. An inhibiting effect by β-alanine was not observed. Immobilization on Sepabeads EC-EP and EC-HFA epoxy supports did not result in an increased thermostability, but did improve operational stability. Nonetheless, enzyme inactivation occurs during catalysis, probably caused by irreversible transamination of the catalytically essential pyruvoyl group. The Royal Society of Chemistry 2009.
- Koenst, Paul M.,Franssen, Maurice C. R.,Scott, Elinor L.,Sanders, Johan P. M.
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- Metal Promoted Cleavage of Diethylenetriamine to give β-Alanine
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An unusual, facile cleavage of C-N bonds of diethylenetriamine (H2NCH2CH2NHCH2CH2NH2 = dien) promoted by the reaction with the rhenium(V) nitrido complex to yield β-alanine (H2NCH2CH2CO2H = β-ala) is reported.
- Bernardi, Roberta,Zanotti, Matteo,Bernardi, Giovanni,Duatti, Adriano
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- OXIDATIVE DEGRADATION OF β- AND γ-AMINO ACIDS BY CONTACT GLOW DISCHARGE ELECTROLYSIS
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The degradation of β- and γ-amino acids in aqueous solutions by contact glow discharge electrolysis (CGDE) was studied.It was found that the reaction is actually a stepwise oxidative degradation by hydroxyl radical produced by CGDE.
- Harada, Kaoru,Terasawa, Jun-ichi
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- Amination of Carboxylic Acids by Reductive Fixation of Molecular Nitrogen by Glow Discharge Against Aqueous Solution
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Amination of several carboxylic acids by reductive fixation of molecular nitrogen was achieved by glow discharge against aqueous solution of these carboxylic acids.The yield of the aminated product is the highest in the case of maleic acid among carboxylic acids used.The addition of hydrochloric acid to the reaction mixture enhances the yield of aminated products.This may be caused by the fact that chloride anion is oxidized by hydroxyl radicals to chlorate ion, and the fixation of molecular nitrogen proceeds under relatively reducing conditions.
- Harada, Kaoru,Igari, Shun-ichiro,Munegumi, Toratane,Takasaki, Michiaki,Shimoyama, Akira
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- Efficient biosynthesis of β-alanine with a tandem reaction strategy to eliminate amide by-product in the nitrilase-catalyzed hydrolysis
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An efficient biosynthesis of β-alanine from 3-aminopropionitrile at high concentration has been developed using a one-pot bienzymatic cascade of a nitrilase and an amidase. The nitrilase BjNIT3397 from Bradyrhizobium japonicum strain USDA110 catalyzes the hydrolysis of 3-aminopropionitrile to β-alanine at the concentration up to 3.0 mol/L with the formation 23% of 3-aminopropanamide. In order to eliminate the by-product 3-aminopropanamide, we cloned and characterized a new amidase from Pseudomonas nitroreducens through gene mining. Under the optimal conditions (50 mmol/L Na2HPO4-NaH2PO4 buffer, pH 6.0, 40 °C), 2.0 mol/L (176 g/L) of 3-aminopropanamide was completely hydrolyzed within 12 h. A tandem reaction system was then established to eliminate the by-product 3-aminopropanamide and increase the production of β-alanine to 90% isolated yield with 15.02 g/(L.h) space-time-yield. These results demonstrated that the tandem reaction strategy was an effective method of eliminating the amide by-products in the nitrilase-catalyzed hydrolysis at high substrate concentration.
- Tao, Yanyang,Han, Chao,Wang, Min,Yao, Peiyuan,Yuan, Jing,Feng, Jinhui,Wu, Qiaqing,Zhu, Dunming
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- Oxidation reaction of aliphatic amines and aminoalcohols in aqueous solution induced by argon arc plasma
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Argon arc plasma induced a powerful and stepwise oxidation reaction including conversion of methyl group to carboxyl group, oxidative cleavage of carbon-carbon bond, and oxidative deamination. Main active species were considered to be hydroxyl radicals by decomposition of water molecules.
- Takasaki, Michiaki,Harada, Kaoru
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- Stereochemistry of Catabolism of the RNA Base Uracil
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A mammalian enzyme system has been used to study the stereochemistry of the catabolism of the pyrimidine uracil (1) to the amino acid β-alanine (4).Use of - and - uracils and of (2)H2O in the incubations yielded sterospecifically deuteriated samples of β-alanine.Assays, involving total synthesis of samples of β-alanine unambigously labelled with deuterium in each of the four C-H bonds have shown that, in the first step in the catabolic process, uracil is reduced by dihydrouracil dehydrogenase with overall anti addition of hydrogen, at the si face at C-6 and the si face at C-5.
- Gani, David,Young, Douglas W.
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- REACTION OF ATOMIC CARBON WITH AMMONIA. THE MECHANISM OF FORMATION OF AMINO ACID PRECURSORS.
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The reaction of arc-generated carbon atoms with ammonia have been investigated. Primary reactions of C//1 are NH insertion and hydrogen abstraction. The NH insertion leads to methyleneamine (1) and HCN. The hydrogen abstraction proceeds in a stepwise manner to generate CH//2, which reacts with NH//3 to produce CH//3NH//2. Hydrolysis of the nonvolatile residue from this reaction produces the amino acids glycine, alanine, N-methylglycine, beta -alanine, and aspartic acid. Serine is also formed when H//2O is included with the reactants. The mechanism of formation of the amino acid precursors is discussed. Labeling experiments (**2H and **1**3C) rule out a hydrogen cyanide polymer as a major precursor to the amino acids. These studies may provide information on extraterrestrial amino acids. Refs.
- Shevlin,McPherson,Melius
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- Kinetics of oxidation of pantothenic acid by chloramine-T in perchloric acid and in alkaline medium catalyzed by OsO4: A mechanistic approach
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Kinetics of oxidation of pantothenic acid (PA) by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in the presence of HClO 4 and NaOH (catalyzed by OsO4) has been investigated at 313 K. The stoichiometry and oxidation products are same in both media; however, their kinetic patterns were found to be different. In acid medium, the rate shows first-order dependence on |CAT|o, fractional-order dependence on |PA|o, and inverse fractional-order on |H+|. In alkaline medium, the rate shows first-order dependence each on |CAT| o and |PA|o and fractional-order dependence on each of |OH-| and |OsO4|. Effects of added p-toluenesulfonamide and halide ions, varying ionic strength, and dielectric constant of medium as well as solvent isotope on the rate of reaction have been investigated. Activation parameters were evaluated, and the reaction constants involved in the mechanisms have been computed. The proposed mechanisms and the derived rate laws are consistent with the observed kinetics.
- Puttaswamy,Jagadeesh
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- Photolytic release of bioactive carboxylic acids from fused pyran conjugates
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New ester cages bearing the coumarin (2H-benzopyran-2-one) skeleton with extended π-systems as phototriggers, for glycine and β-alanine, as models of carboxylic acid bifunctional molecules with biological relevance, were evaluated under photolysis conditions at 254, 300, 350 and 419 nm of irradiation in a RPR-100 photochemical reactor. The processes were followed by HPLC-UV detection and 1H NMR with collection of kinetic data. The results showed a correlation between the photolysis efficiency and the increasing extension of the conjugation for both glycine and β-alanine, showing that the 7-aminocoumarin afforded the best results at all wavelengths tested. From a study of the time-resolved fluorescence behaviour, these compounds were also found to exhibit more complex fluorescence decay kinetics. This was attributed to the presence of conjugated and non-conjugated coumarin species.
- Concei??o, Rafaela,Hungerford, Graham,Costa, Susana P.G.,Gon?alves, M. Sameiro T.
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- Catalytic reaction of model zinc(II) complex for active sites of mono-nuclear zinc-peptidases
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Catalytic hydrolysis reaction of amide by designed zinc-complex model for active sites of mono-nuclear zinc-peptidases has been investigated. The effect of carboxylate ligand of the model complex on hydrolysis activity was revealed by kinetic analyses.
- Ogawa, Kazuya,Nakata, Kou,Ichikawa, Kazuhiko
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- Development and Application of Efficient Ag-based Hydrogenation Catalysts Prepared from Rice Husk Waste
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The development of strategies for the sustainable management and valorization of agricultural waste is of outmost importance. With this in mind, we report the use of rice husk (RH) as feedstock for the preparation of heterogeneous catalysts for hydrogenation reactions. The catalysts were prepared by impregnating the milled RH with a silver nitrate solution followed by carbothermal reduction. The composition and morphology of the prepared catalysts were fully assessed by IR, AAS, ICP-MS, XPS, XRD and STEM techniques. This novel bio-genic silver-based catalysts showed excellent activity and remarkable selectivity in the hydrogenation of nitro groups in both aromatic and aliphatic substrates, even in the presence of reactive functionalities like halogens, carbonyls, borate esters or nitriles. Recycling experiments showed that the catalysts can be easily recovered and reused multiple times without significant drop in performance and without requiring re-activation.
- Unglaube, Felix,Kreyenschulte, Carsten Robert,Mejía, Esteban
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p. 2583 - 2591
(2021/04/09)
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- A plug-and-play chemobiocatalytic route for the one-pot controllable synthesis of biobased C4 chemicals from furfural
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Chemobiocatalytic selective transformation is an attractive yet challenging task, due to the incompatibility issues between different types of catalysts. In this work, one-pot, multi-step cascades integrating biocatalysis with organo-, base- and photocatalysis in a plug-and-play fashion were constructed for the controllable synthesis of eight C4 chemicals from furfural. Furfural was converted to 5-hydroxy-2(5H)-furanone (HFO) by sequential biocatalytic oxidation and photooxygenation in phosphate buffer, in >90% yields. Ring opening and concurrent isomerization of HFO to fumaric semialdehyde (FSA) were readily realized under mild conditions by a weakly basic resin (e.g., DVB resin). The versatile intermediate FSA could be oxidized to fumaric acid (FA) using a laccase-2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) system, which was further upgraded to amino acids including l-aspartic acid (l-Asp) and β-alanine (β-Ala) by whole-cell catalysis. Notably, amino acids were obtained from biobased furfural in a one-pot, four-step process with yields of up to 75%, without the isolation of any intermediates. Besides, the scale-up synthesis of l-Asp was demonstrated. This work demonstrates the great potential of the combination of chemo- and biocatalysis for selective furfural valorization.
- Huang, Yi-Min,Lu, Guang-Hui,Zong, Min-Hua,Cui, Wen-Jing,Li, Ning
-
supporting information
p. 8604 - 8610
(2021/11/16)
-
- Genomics-driven discovery of a new cyclodepsipeptide from the guanophilic fungusAmphichorda guana
-
Two potential non-ribosomal peptide synthetases (NRPSs) were identified in the genome of a guanophilic fungusAmphichorda guanaby bioinformatics analysis and gene knockout experiments. Liquid chromatography coupled with mass spectrometry (LC-MS) guided isolation led to the discovery of a new cyclodepsipeptide isaridin H (1) and seven known analogs, desmethylisaridin E (2), isaridin E (3), isariin A (4), iso-isariin B (5), iso-isariin D (6), isariin E (7), and nodupetide (8). The absolute configuration of isaridin H (1) was achieved by Marfey's method. Isaridin H (1) showed significant antifungal activity againstBotrytis cinereaandAlternaria solani.
- Liang, Min,Lyu, Hai-Ning,Ma, Zi-Ying,Li, Er-Wei,Cai, Lei,Yin, Wen-Bing
-
p. 1960 - 1964
(2021/03/16)
-
- Recycling method of beta,beta-iminodipropionitrile and application
-
The invention provides a recycling method of beta,beta-iminodipropionitrile and application, and relates to the technical field of waste recycling. According to the recycling method, by adopting a specific reaction synthesis route, the beta,beta-iminodipropionitrile finally generates calcium pantothenate with wide application, and the recycling method not only reduces hazardous waste emission and treatment and lowers the hazardous waste treatment cost, but also realizes the purpose of turning waste into wealth from beta,beta-iminodipropionitrile, and the utilization value of beta,beta-iminodipropionitrile is greatly improved. The invention further provides application of the recycling method of the beta,beta-iminodipropionitrile, and in view of the advantages of the recycling method of the beta,beta-iminodipropionitrile, a new process route is provided for preparing calcium pantothenate.
- -
-
Paragraph 0093; 0096-0097; 0122; 0125-0126
(2021/05/26)
-
- INTEGRATED METHODS AND SYSTEMS FOR PRODUCING AMIDE AND NITRILE COMPOUNDS
-
Provided herein are integrated methods and systems for the production of acrylamide and acrylonitrile compounds and other compounds from at least beta-lactones and/or beta-hydroxy amides.
- -
-
Paragraph 00089-00092; 00099
(2020/09/30)
-
- 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.
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p. 289 - 296
(2020/05/18)
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- Organocatalytic Decarboxylation of Amino Acids as a Route to Bio-based Amines and Amides
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Amino acids obtained by fermentation or recovered from protein waste hydrolysates represent an excellent renewable resource for the production of bio-based chemicals. In an attempt to recycle both carbon and nitrogen, we report here on a chemocatalytic, metal-free approach for decarboxylation of amino acids, thereby providing a direct access to primary amines. In the presence of a carbonyl compound the amino acid is temporarily trapped into a Schiff base, from which the elimination of CO2 may proceed more easily. After evaluating different types of aldehydes and ketones on their activity at low catalyst loadings (≤5 mol%), isophorone was identified as powerful organocatalyst under mild conditions. After optimisation many amino acids with a neutral side chain were converted in 28–99 % yield in 2-propanol at 150 °C. When the reaction is performed in DMF, the amine is susceptible to N-formylation. This consecutive reaction is catalysed by the acidity of the amino acid reactant itself. In this way, many amino acids were efficiently transformed to the corresponding formamides in a one-pot catalytic system.
- Claes, Laurens,Janssen, Michiel,De Vos, Dirk E.
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p. 4297 - 4306
(2019/08/26)
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- Modular Enzymatic Cascade Synthesis of Vitamin B5 and Its Derivatives
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Access to vitamin B5 [(R)-pantothenic acid] and both diastereoisomers of α-methyl-substituted vitamin B5 [(R)- and (S)-3-((R)-2,4-dihydroxy-3,3-dimethylbutanamido)-2-methylpropanoic acid] was achieved using a modular three-step biocatalytic cascade involving 3-methylaspartate ammonia lyase (MAL), aspartate-α-decarboxylase (ADC), β-methylaspartate-α-decarboxylase (CrpG) or glutamate decarboxylase (GAD), and pantothenate synthetase (PS) enzymes. Starting from simple non-chiral dicarboxylic acids (either fumaric acid or mesaconic acid), vitamin B5 and both diastereoisomers of α-methyl-substituted vitamin B5, which are valuable precursors for promising antimicrobials against Plasmodium falciparum and multidrug-resistant Staphylococcus aureus, can be generated in good yields (up to 70 %) and excellent enantiopurity (>99 % ee). This newly developed cascade process may be tailored and used for the biocatalytic production of various vitamin B5 derivatives by modifying the pantoyl or β-alanine moiety.
- Abidin, Mohammad Z.,Saravanan, Thangavelu,Zhang, Jielin,Tepper, Pieter G.,Strauss, Erick,Poelarends, Gerrit J.
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supporting information
p. 17434 - 17438
(2018/11/10)
-
- Methods for synthesizing Beta-calcium aminopropionate and D-calcium pantothenate
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The invention relates to the field of biochemical engineering, and discloses methods for synthesizing Beta-calcium aminopropionate and D-calcium pantothenate. According to the methods, acrylonitrile is utilized to react with liquid ammonia to prepare Beta-aminopropionitrile; nitrilase is utilized to catalyze to hydrolyze the Beta-aminopropionitrile to generate Beta-aminopropionic acid, afterwards,the Beta-aminopropionic acid reacts with a calcifying agent to synthesize the Beta-calcium aminopropionate, then the Beta-calcium aminopropionate generates an acylation reaction with D-pantolactone,and the D-calcium pantothenate is obtained by filtration and drying. The synthesis methods provided by the invention do not need to use a strong base to hydrolyze the Beta-aminopropionitrile, also donot need to use ion exchange resin to extract the Beta-aminopropionic acid, are used for effectively reducing the generation of a by-product salt, is easily amplified, is used for realizing continuousproduction, and has a quite good industrial application prospect, and a technique is simple, convenient, easy and feasible.
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Paragraph 0036; 0037; 0038; 0039; 0040; 0041
(2018/06/26)
-
- Microchannel reactor-based cyano hydrolysis reaction method
-
The invention discloses a microchannel reactor-based cyano compound hydrolysis reaction method, and particularly, a compound comprising a cyano group in the molecule has the cyano hydrolysis reactionby using a microchannel reactor under the action of alkaline or acid-alkaline substances. By using the microchannel reactor in the process, the raw material is instantaneously evenly mixed and efficiently transfers heat; the most important danger of rushing of the material in the production process, caused by hydrolysis of the cyano compound through the alkali, is avoided; meanwhile, the equivalence ratio of the raw material in the reaction process is also reduced; the side reaction is reduced; the reaction time is shortened to dozens of minutes or even dozens of seconds. In a word, the process improves the operation safety of the reaction, the safe enlarged production of the cyano compound is realized, the time for the hydrolysis reaction of the cyano compound is shortened, the reaction selectivity and the reaction efficiency are improved, the energy consumption of the production is reduced, the use ratio of the raw material is increased, the production process is more environmentallyfriendly, the production cost is low, meanwhile, the used equipment occupies a small area, the production capacity of the equipment is high, and the production efficiency and the production capacityare greatly improved.
- -
-
Paragraph 0036-0048
(2018/08/04)
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- ACTIVITY-ENHANCING SUPPLEMENT
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An activity-enhancing supplement can include niacin and at least two ingredients selected from citrulline, agmatine, an endurance enhancer, a counteracting agent, a nitrogen-containing compound, a muscle building component, branched chain amino acid, and combinations thereof.
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-
-
- Identification of Cyclic Depsipeptides and Their Dedicated Synthetase from Hapsidospora irregularis
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Seven cyclic depsipeptides were isolated from Hapsidospora irregularis and structurally characterized as the calcium channel blocker leualacin and six new analogues based on the NMR and HRESIMS data. These new compounds were named leualacins B-G. The absolute configurations of the amino acids and 2-hydroxyisocaproic acids were determined by recording the optical rotation values. Biological studies showed that calcium influx elicited by leualacin F in primary human lobar bronchial epithelial cells involves the TRPA1 channel. Through genome sequencing and targeted gene disruption, a noniterative nonribosomal peptide synthetase was found to be involved in the biosynthesis of leualacin. A comparison of the structures of leualacin and its analogues indicated that the A2 and A4 domains of the leualacin synthetase are substrate specific, while A1, A3, and A5 can accept alternative precursors to yield new molecules.
- Zhang, Shuwei,Qiu, Yixing,Kakule, Thomas B.,Lu, Zhenyu,Xu, Fuchao,Lamb, John G.,Reilly, Christopher A.,Zheng, Yong,Sham, Shing Wo Simon,Wang, Wei,Xuan, Lijiang,Schmidt, Eric W.,Zhan, Jixun
-
p. 363 - 370
(2017/03/08)
-
- A process for the preparation of β-alanine (by machine translation)
-
The invention discloses a novel synthetic process of beta-aminopropionic acid. Cyanoacetate serves as a raw material and is subjected to hydrogenation reduction to become beta-amino ethyl propionate, which is then hydrolyzed and crystallized through high acidic resins to obtain a beta-aminopropionic acid finished product, wherein, hydrogenation is the key of the process.
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-
Paragraph 0017; 0018
(2018/02/04)
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- PROCESS FOR THE REDUCTION OF NITRO DERIVATIVES TO AMINES
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Disclosed is a novel process for the reduction of nitro groups to amino derivatives, based on the use of trichlorosilane and an organic base, which is efficient from the chemical standpoint and of wide general applicability.
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Page/Page column 6
(2014/03/26)
-
- Immunomodulatory peptides
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The invention relates to peptides derivatized with a hydrophilic polymer which, in some embodiments, bind to human FcRn and inhibit binding of the Fc portion of an IgG to an FcRn, thereby modulating serum IgG levels. The disclosed compositions and methods may be used in some embodiments, for example, in treating autoimmune diseases and inflammatory disorders. The invention also relates, in further embodiments, to methods of using and methods of making the peptides of the invention.
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- Meteorites as catalysts for prebiotic chemistry
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From outer space: Twelve meteorite specimens, representative of their major classes, catalyse the synthesis of nucleobases, carboxylic acids, aminoacids and low-molecular-weight compounds from formamide (see figure). Different chemical pathways are identified, the yields are high for a prebiotic process and the products come in rich and composite panels.
- Saladino, Raffaele,Botta, Giorgia,Delfino, Michela,Di Mauro, Ernesto
-
p. 16916 - 16922
(2014/01/06)
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- MULTIMER GLYCOSYLATED NUCLEIC ACID BINDING PROTEIN CONJUGATES AND USES THEREOF
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The technology relates in part to multimer conjugates comprising a scaffold linked to two or more polypeptides that specifically interact with a nucleic acid containing beta-D-glucosyl-hydroxymethylcytosine or beta-D-glucosyl-hydroxymethyluracil. The scaffold can be chosen from an antibody, an antibody fragment, a multimerized binding partner that interacts with a binding partner counterpart in each of the polypeptides, a polymer, and a polyfunctional molecule. The polypeptides can be from a kinetoplastid flagellate organism and may comprise a full-length native or modified protein or a fragment thereof that specifically interacts with the beta-D-glucosyl-hydroxymethylcytosine and/or the beta-D-glucosyl-hydroxymethyluracil in the nucleic acid. The conjugates provided herein can be used to detect the presence, absence or amount of beta-D-glucosyl-hydroxymethylcytosine and/or beta-D-glucosyl-hydroxymethyluracil-containing nucleic acid in a sample.
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- Direct C-H arylation of purine on solid phase and its use for chemical libraries synthesis
-
C8-H direct arylation of purine derivatives immobilized on Wang resin is described. The purine skeleton was immobilized via C 6-regioselective substitution of 2,6-dichloropurine with polymer-supported amines. After N9-alkylation with two different alkyl iodides and C2 substitution with two selected amines, reaction conditions for C8-H arylation were developed and optimized. Various aryl bromides and aryl iodides were used for the reaction affording the target 2,6,8,9-tetrasubstituted purines in very good purity. The same reaction conditions were also applied for the synthesis of 2,6,8-trisubstituted purines, however, yields were lower. The methodology is applicable for high throughput synthesis of chemical libraries comprised of purine scaffold.
- Vankova, Barbora,Krchnak, Viktor,Soural, Miroslav,Hlavac, Jan
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scheme or table
p. 496 - 500
(2011/11/06)
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- Beta-alanine/alpha-ketoglutarate aminotransferase for 3-hydroxypropionic acid production
-
The present disclosure provides novel beta-alanine/alpha ketoglutarate aminotransferase nucleic acid and protein sequences having increased biological activity. Also provided are cells containing such enzymes, as well as methods of their use, for example to produce malonyl semialdehyde and downstream products thereof, such as 3-hydroxypropionic acid and derivatives thereof.
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- Phototriggering of neuroactive amino acids from 5,6-benzocoumarinyl conjugates
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Uncaging of several neuroactive amino acids, namely β-alanine, tyrosine, 3,4-dihydroxyphenylalanine (DOPA) and glutamic acid from the corresponding 5,6-benzocoumarinyl conjugates was carried out by irradiation at different wavelengths and in different solvent systems. The release of the various amino acids was faster in ACN/HEPES buffer mixtures and for the tyrosine conjugate, an increase in the photolysis reaction rates and the quantitative uncaging of the amino acid was associated with increasing water content in the solvent mixture.
- Fernandes, Maria José G.,Costa, Susana P.G.,Gonalves, M. Sameiro T.
-
experimental part
p. 2422 - 2426
(2011/05/06)
-
- Structural and functional characterization of plant aminoaldehyde dehydrogenase from pisum sativum with a broad specificity for natural and synthetic aminoaldehydes
-
Aminoaldehyde dehydrogenases (AMADHs, EC 1.2.1.19) belong to the large aldehyde dehydrogenase (ALDH) superfamily, namely, the ALDH9 family. They oxidize polyamine-derived ω-aminoaldehydes to the corresponding ω-amino acids. Here, we report the first X-ray structures of plant AMADHs: two isoenzymes, PsAMADH1 and PsAMADH2, from Pisum sativum in complex with β-nicotinamide adenine dinucleotide (NAD+) at 2.4 and 2.15 A resolution, respectively. Both recombinant proteins are dimeric and, similarly to other ALDHs, each monomer is composed of an oligomerization domain, a coenzyme binding domain and a catalytic domain. Each subunit binds NAD+ as a coenzyme, contains a solvent-accessible C-terminal peroxisomal targeting signal (type 1) and a cation bound in the cavity close to the NAD+ binding site. While the NAD+ binding mode is classical for PsAMADH2, that for PsAMADH1 is unusual among ALDHs. A glycerol molecule occupies the substrate binding site and mimics a bound substrate. Structural analysis and substrate specificity study of both isoenzymes in combination with data published previously on other ALDH9 family members show that the established categorization of such enzymes into distinct groups based on substrate specificity is no more appropriate, because many of them seem capable of oxidizing a large spectrum of aminoaldehyde substrates. PsAMADH1 and PsAMADH2 can oxidize N,N,N-trimethyl-4-aminobutyraldehyde into γ-butyrobetaine, which is the carnitine precursor in animal cells. This activity highly suggests that in addition to their contribution to the formation of compatible osmolytes such as glycine betaine, β-alanine betaine and γ-aminobutyric acid, AMADHs might participate in carnitine biosynthesis in plants.
- Tylichova, Martina,Kopecny, David,Morera, Solange,Briozzo, Pierre,Lenobel, Rene,Snegaroff, Jacques,Sebela, Marek
-
experimental part
p. 870 - 882
(2011/04/24)
-
- 2-Oxo-2H-benzo[h]benzopyran as a new light sensitive protecting group for neurotransmitter amino acids
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Aiming at the development of new benzopyran-based photocleavable protecting groups, novel chloromethylated and hydroxymethylated 2-oxo-2H-benzo[h] benzopyran derivatives bearing a methoxy substituent were designed and used in the synthesis of a series of fluorescent bioconjugates, by linking through an ester or urethane bond to several model neurotransmitter amino acids (glycine, alanine, β-alanine and γ-aminobutyric acid, GABA). The resulting fluorescent bioconjugates with emission in the visible range and high fluorescent quantum yields, were subjected to photocleavage reaction in methanol/HEPES buffer (80:20) solution at different wavelengths of irradiation (250, 300, 350 and 419 nm) and photocleavage kinetic data were obtained.
- Soares, Ana M. S.,Costa, Susana P. G.,Goncalves, M. Sameiro T.
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experimental part
p. 121 - 133
(2010/09/07)
-
- 3-Fluoroaspartate and pyruvoyl-dependant aspartate decarboxylase: Exploiting the unique characteristics of fluorine to probe reactivity and binding
-
Fluorine-containing amino acids have been used with great success as mechanism-based inhibitors of pyridoxal phosphate (PLP)-dependent enzymes, and the influence of fluorine on the conformation of molecules has also been extensively studied and practically exploited. In this study, we sought to use these unique characteristics to probe the reactivity and binding of aspartate decarboxylase (ADC) enzymes, which are members of the small class of pyruvoyl-dependant decarboxylases. Since ADC activity has been shown to be essential to the virulence of Mycobacterium tuberculosis, information gained in this manner could be used for the development of inhibitors that selectively target pyruvoyl-dependent enzymes such as ADC, without affecting PLP-dependent enzymes in the host. For this purpose, we synthesized the L-erythro and L-threo isomers of 3-fluoroaspartate and tested their ability to act as substrates and/or inhibitors of the M. tuberculosis and Escherichia coli ADC enzymes. Trapping and MS-based binding analysis was additionally used to confirm that both isomers enter the enzymes' active sites. Our studies show that both isomers undergo single turnover decarboxylation and fluorine elimination reactions to give enamine products that can be trapped within the active site. Interestingly, the enamine/ADC complex that forms from the lerythro (but not the L-threo) isomer is sufficiently stable that it can be observed even without any trapping. This finding suggests that the two 3-fluoroaspartates maintain different conformations within the ADC active site, which leads to the enamine products with configurations of different stabilities. Taken together, our results provide new insights for the development of cofactor-specific inhibitors, and confirm the utility of fluorine as a unique tool for probing reactivity and binding profiles within enzymes.
- De Villiers, Jandre,Koekemoer, Lizbe,Strauss, Erick
-
supporting information; experimental part
p. 10030 - 10041
(2011/01/13)
-
- COSMETIC COMPOSITION
-
A cosmetic agent, in particular a styling agent, containing, in a cosmetically acceptable carrier, a) at least one copolymer A made of at least one monomer A1 selected from acrylic acid, methacrylic acid, acrylic acid alkyl esters, and methacrylic acid alkyl esters, and at least one amphoteric monomer A2 selected from (meth)acryloylalkylbetaines of formula (A2-I) and (meth)acryloylalkylamine oxides of formula (A2-II), such that in formula (A2-I) and in formula (A2-II), R1 denotes H or CH3, R2 and R3, mutually independently in each case, denote optionally branched C1-10 alkyl, and n denotes an integer from 1 to 20, and b) at least one film-forming and/or setting amphoteric polymer B different from copolymer A; and use of the agents for the temporary deformation of hairs.
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- Purification and characterization of the first archaeal glutamate decarboxylase from Pyrococcus horikoshii
-
Glutamate decarboxylase (GAD) from the archaeon Pyrococcus horikoshii was successfully expressed and purified, with the aim of developing a hyperthermostable GAD for industrial applications. Its biochemical properties were different from those reported for other GADs. The enzyme had broad substrate specificity, and its optimum pH and temperature were pH 8.0 and >97°C.
- Kim, Han-Woo,Kashima, Yasuhiro,Ishikawa, Kazuhiko,Yamano, Naoko
-
body text
p. 224 - 227
(2009/06/18)
-
- PROCESS FOR THE SYNTHESIS OF NA- BETA-ALANINATE AND CALCIUM PANTOTHENATE
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In a process for the preparation of Na-β-alaninate from β-amino-propionitrile ready for the condensation with pantolactone to pantothenate the improvement of obtaining Na-β-alaninate as a solution in an alcohol, which improvement comprises carrying out the hydrolysis of β-amino-propionitrile in water and then making a solvent exchange from water to an alcohol, thus achieving that the final β-alaninate mixture contains side- or by-products in amounts only, which do not negatively influence the-pantothenate quality.
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Page/Page column 5-6
(2009/03/07)
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- A mild Boc deprotection and the importance of a free carboxylate
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We report a facile and rapid removal of Boc protecting groups using microwave heating in H2O, with deprotection only requiring a free carboxylic acid group in the starting material. Unlike previous approaches, no additional reagents are required.
- Thaqi, Ali,McCluskey, Adam,Scott, Janet L.
-
supporting information; experimental part
p. 6962 - 6964
(2009/04/07)
-
- Structure-stability correlations for imine formation in aqueous solution
-
Imine formation between 25 aldehydes and 13 amines in aqueous solution in the pH range 7-11 was studied by 1H NMR spectroscopy. A three-parameter linear equation correlating logarithms of imine formation constants with pKa and HOMO energies of amines and LUMO energies of aldehydes is proposed. In view of the widespread occurrence of imine-forming processes in both chemistry and biology, the data presented are of significance for physical organic chemistry and of particular interest for dynamic combinatorial chemistry. Copyright
- Godoy-Alcantar,Yatsimirsky, Anatoly K.,Lehn
-
p. 979 - 985
(2007/10/03)
-
- Conjugate addition reactions for the controlled delivery of pharmaceutically active compounds
-
The invention features polymeric biomaterials formed by nucleophilic addition reactions to conjugated unsaturated groups. These biomaterials may be used for medical treatments.
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- Frangible compounds for pathogen inactivation
-
Compounds and methods for inactivating pathogens in materials are described, including compositions and methods for inactivating pathogens in biological materials such as red blood cell preparations and plasma. The compounds and methods may be used to treat materials intended for in vitro or in vivo use, such as clinical testing or transfusion. The compounds are designed to specifically bind to and react with nucleic acid, and then to degrade to form breakdown products. The degradation reaction is preferably slower than the reaction with nucleic acid.
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- Method for producing carboxylic acid by alcohol oxidation
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The invention relates to a method for oxidizing primary amino alcohols, primary or secondary alkenols or alkinols into the corresponding acids or ketones. According to said method, a primary amino alcohol or a primary or secondary alkenol or alkinol is oxidized in the form of a substrate, in the presence of an equimolar quantity of periodate or a molar excess thereof in relation to the alcoholic hydroxy groups and catalytic quantities of dichromate or CrO3 and in the presence of an acid in water, a water/solvent mixture or a solvent at a temperature of ?20 ° C. to +50 ° C., to produce the corresponding acid or the corresponding ketone.
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- Absolute rate constants for the formation of nitrogen-centred radicals from chloramines/amides and their reactions with antioxidants
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Pulse radiolysis techniques have been employed to investigate the one-electron reduction of a variety of chloramines and chloramides. These include models for the side-chain of Lys (6-aminohexanoic acid chloramine and α-N-acetyl-Lys chloramine), Gly chloramine, β-alanine chloramine and two models of protein backbone amides, the chloramides of cyclo-(Gly)2 and cyclo-(Ala)2. The molar absorption coefficients and stabilities of these chloramines/amides have been determined. The one-electron reduction of these chloramine/amide species by hydrated electrons occurs with second-order rate constants of the order of 109-1010 M-1 s-1, and results in cleavage of the N-Cl bonds to yield nitrogen-centred radicals and chloride ions (as measured by high performance ion chromatography). The reactivities of the nitrogen-centred radicals have been investigated with the readily oxidisable quenchers, hydroquinone and Trolox. These quenchers were used as models of the in vivo antioxidants, ubiquinol-10 and α-tocopherol, and react with second-order rate constants between 2 × 107 and 1 × 108 M-1 s-1. No evidence was obtained in these pulse radiolysis experiments for a rapid rearrangement of the oxidising nitrogen-centred radicals to reducing carbon-centred radicals, though such reactions have been indicated in previous EPR studies.
- Pattison, David I.,Davies, Michael J.,Asmus, Klaus-Dieter
-
p. 1461 - 1467
(2007/10/03)
-
- Raney copper
-
Raney copper which is doped with at least one metal from the group comprising iron and/or noble metals is used as a catalyst in the dehydrogenation of alcohols.
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- 2-aminopyridine derivatives and combinatorial libraries thereof
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The present invention relates to novel 2-aminopyridine derivative compounds of the following formula: wherein R1to R5have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminopyridine derivative compounds.
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- Composition of matter having bioactive properties
-
Particles of coordinated complex comprising a basic, hydrous polymer and a capacitance adding compound, as well as methods for their production, are described. These complexes exhibit a high degree of bioactivity making them suitable for a broad range of applications through their incorporation into conventional vehicles benefiting from antimicrobial and similar properties.
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- Frangible compounds for pathogen inactivation
-
Compounds and methods for inactivating pathogens in materials are described, including compositions and methods for inactivating pathogens in biological materials such as red blood cell preparations and plasma. The compounds and methods may be used to treat materials intended for in vitro or in vivo use, such as clinical testing or transfusion. The compounds are designed to specifically bind to and react with nucleic acid, and then to degrade to form breakdown products. The degradation reaction is preferably slower than the reaction with nucleic acid.
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