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A Photoregulated Racemase Mimic
The racemase enzymes convert L-amino acids to their D-isomer. The reaction proceeds through a stepwise deprotonation–reprotonation mechanism that is assisted by a pyridoxal phosphate (PLP) coenzyme. This work reports a PLP–photoswitch–imidazole triad where the racemization reaction can be controlled by light by tweaking the distance between the basic residue and the reaction centre.
Saha, Monochura,Hossain, Munshi Sahid,Bandyopadhyay, Subhajit
supporting information
p. 5220 - 5224
(2021/01/18)

Mechanistic insight into metal ion-catalyzed transamination
Several classes of biological reactions that are mediated by an enzyme and a co-factor can occur, to a slower extent, not only without the enzyme but even without the co-factor, under catalysis by metal ions. This observation has led to the proposal that metabolic pathways progressively evolved from using inorganic catalysts to using organocatalysts of increasing complexity. Transamination, the biological process by which ammonia is transferred between amino acids and α-keto acids, has a mechanism that has been well studied under enzyme/co-factor catalysis and under co-factor catalysis, but the metal ion-catalyzed variant was generally studied mostly at high temperatures (70-100 °C), and the details of its mechanism remained unclear. Here, we investigate which metal ions catalyze transamination under conditions relevant to biology (pH 7, 20-50 °C) and study the mechanism in detail. Cu2+, Ni2+, Co2+, and V5+ were identified as the most active metal ions under these constraints. Kinetic, stereochemical, and computational studies illuminate the mechanism of the reaction. Cu2+ and Co2+ are found to predominantly speed up the reaction by stabilizing a key imine intermediate. V5+ is found to accelerate the reaction by increasing the acidity of the bound imine. Ni2+ is found to do both to a limited extent. These results show that direct metal ion-catalyzed amino group transfer is highly favored even in the absence of co-factors or protein catalysts under biologically compatible reaction conditions.
Mayer, Robert J.,Kaur, Harpreet,Rauscher, Sophia A.,Moran, Joseph
supporting information
p. 19099 - 19111
(2021/11/22)

Rational engineering ofAcinetobacter tandoiiglutamate dehydrogenase for asymmetric synthesis ofl-homoalanine through biocatalytic cascades
l-Homoalanine, a useful building block for the synthesis of several chiral drugs, is generally synthesized through biocascades using natural amino acids as cheap starting reactants. However, the addition of expensive external cofactors and the low efficiency of leucine dehydrogenases towards the intermediate 2-ketobutyric acid are two major challenges in industrial applications. Herein, a dual cofactor-dependent glutamate dehydrogenase fromAcinetobacter tandoii(AtGluDH) was identified to help make full use of the intracellular pool of cofactors when using whole-cell catalysis. Through reconstruction of the hydrophobic network between the enzyme and the terminal methyl group of the substrate 2-ketobutyric acid, the strict substrate specificity ofAtGluDH towards α-ketoglutarate was successfully changed, and the activity obtained by the most effective mutant (K76L/T180C) was 17.2 times higher than that of the wild-type protein. A three-enzyme co-expression system was successfully constructed in order to help release the mass transfer restriction. Using 1 Ml-threonine, which is close to the solubility limit, we obtained a 99.9% yield ofl-homoalanine in only 3.5 h without adding external coenzymes to the cascade, giving 99.9% ee and a 29.2 g L?1h?1space-time yield. Additionally, the activities of the engineeredAtGluDH towards some other hydrophobic amino acids were also improved to 1.1-11.2 fold. Therefore, the engineering design of some dual cofactor-dependent GluDHs could not only eliminate the low catalytic activity of unnatural substrates but also enhance the cofactor utilization efficiency of these enzymes in industrial applications.
Diao, Shiqing,Jiang, Shuiqin,Liu, Yan,Sun, Yangyang,Wang, Hualei,Wang, Liuzhu,Wei, Dongzhi
p. 4208 - 4215
(2021/06/30)

Biocatalysed synthesis of chiral amines: continuous colorimetric assays for mining amine-transaminases
In the course of our research aimed at the design of new biocatalytic processes for the enantioselective synthesis of chiral amines, we have developed new continuous assays for the screening of amine-transaminase collections. These assays are based on the use of hypotaurine as an irreversible amine donor. This β-aminosulfinic acid is converted upon transamination into 2-oxoethylsulfinic acid, which instantaneously decomposes into acetaldehyde and sulfite ions that can be easily detected by spectrophotometry using Ellman's reagent. Two complementary assays were developed based on this titration method. Firstly, a direct assay allowed detection of various transaminases able to use hypotaurine as an amino donor. In a second coupled assay,l-alanine is used as a generic donor substrate of amine-transaminases and is regenerated using an auxiliary hypotaurine-transaminase. The powerful and complementary nature of both assays was demonstrated through the screening of a collection of 549 amine-transaminases from biodiversity, thus allowing the discovery of a variety of valuable new biocatalysts for use in synthetic processes.
Gourbeyre, Léa,Heuson, Egon,Charmantray, Franck,Hélaine, Virgil,Debard, Adrien,Petit, Jean-Louis,de Berardinis, Véronique,Gefflaut, Thierry
p. 904 - 911
(2021/02/26)

The Effect of Visible Light on the Catalytic Activity of PLP-Dependent Enzymes
Pyridoxal 5’-phosphate (PLP)-dependent enzymes are a versatile class of biocatalysts and feature a variety of industrial applications. However, PLP is light sensitive and can cause inactivation of enzymes in certain light conditions. As most of the PLP-dependent enzymes are usually not handled in dark conditions, we evaluated the effect of visible light on the activity of PLP-dependent enzymes during production as well as transformation. We tested four amine transaminases, from Chromobacterium violaceum, Bacillus megaterium, Vibrio fluvialis and a variant from Arthrobacter species as well as two lysine decarboxylases, from Selenomonas ruminantium and the LDCc from Escherichia coli. It appeared that five of these six enzymes suffered from a significant decrease in activity by up to 90 % when handled in laboratory light conditions. Surprisingly, only the amine transaminase variant from Arthrobacter species appeared to be unaffected by light exposure and even showed an activation to 150 % relative activity over the course of 6 h regardless of the light conditions.
Gerlach, Tim,Nugroho, David Limanhadi,Rother, D?rte
p. 2398 - 2406
(2021/04/05)

Synthesis of new amides based on N-Phthaloyl-α-Amino Acids
N-phthaloyl derivatives of aliphatic α-amino acids were synthesized using phthalanhydride under standard conditions. The optimization reaction carried out by the thermal method to obtain the amides of these N-phthaloyl amino acids resulted in transimitted rather than amidation. The target amides of N-phthaloyl-α-amino acids were obtained by acylation of the amine with the corresponding acid chloroanhydrides in dichloromethane. These results were compared with the results of a similar acylation in a non-polar solvent (benzene). The dependence of the direction of the reaction on the duration of the acylation and the amount of amine used was established. The conditions for the formation of the corresponding N-phthaloyl-α-amino acid amides and asymmetric phthalic acid diamides were found. It is noteworthy that the formation of diamides is directly proportional to the equivalent amount of amine and the duration of the reaction, which makes it possible to purposefully control the synthesis in one reactor.
Tukhtaev,Yusupov,Vinogradova
p. 3049 - 3058
(2021/05/28)

Highly Efficient Synthesis of Amino Acids by Amination of Bio-Derived Hydroxy Acids with Ammonia over Ru Supported on N-Doped Carbon Nanotubes
The amino acids have extensive applications, and their productions from biomass-derived feedstocks are very attractive. In this work, the synthesis of amino acids by amination of bio-derived hydroxy acids with ammonia over different metallic nano-catalysts supported on various supports is studied. It is found that Ru nano-catalysts on the nitrogen-doped carbon nanotubes (Ru/N?CNTs) have an outstanding performance for the reaction. Different hydroxy acids can be catalytically converted into the corresponding amino acids with yields up to 70.0 % under mild conditions, which is higher than those reported. The reasons for the high efficiency of the catalyst are investigated, and the reaction pathway is proposed on the basis of control experiments.
Xie, Zhenbing,Chen, Bingfeng,Peng, Fangfang,Liu, Mingyang,Liu, Huizhen,Yang, Guanying,Han, Buxing
p. 5683 - 5689
(2020/09/21)

Scope and limitations of reductive amination catalyzed by half-sandwich iridium complexes under mild reaction conditions
The conversion of aldehydes and ketones to 1° amines could be promoted by half-sandwich iridium complexes using ammonium formate as both the nitrogen and hydride source. To optimize this method for green chemical synthesis, we tested various carbonyl substrates in common polar solvents at physiological temperature (37 °C) and ambient pressure. We found that in methanol, excellent selectivity for the amine over alcohol/amide products could be achieved for a broad assortment of carbonyl-containing compounds. In aqueous media, selective reduction of carbonyls to 1° amines was achieved in the absence of acids. Unfortunately, at Ir catalyst concentrations of 1 mM in water, reductive amination efficiency dropped significantly, which suggest that this catalytic methodology might be not suitable for aqueous applications where very low catalyst concentration is required (e.g., inside living cells).
Nguyen, Dat P.,Sladek, Rudolph N.,Do, Loi H.
supporting information

(2020/07/15)

PERMANENTLY POLARIZED HYDROXYAPATITE, A PROCESS FOR ITS MANUFACTURE AND USES THEREOF
The present invention relates to a permanently polarized hydroxyapatite and a composition or material comprising thereof. The present invention further relates to a process for obtaining a permanently polarized hydroxyapatite and to different uses of the permanently polarized hydroxyapatite or the composition or material comprising thereof.
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Paragraph 0191-0199

(2020/07/04)

Catalytic Production of Alanine from Waste Glycerol
Chemical synthesis of amino acids directly from biomass feedstock is rare. Reported here is a one-step protocol to convert crude glycerol, from the biodiesel industry, into 43 % alanine over a Ru1Ni7/MgO catalyst. The multifunctional catalytic system promotes glycerol conversion into lactic acid, and then into alanine. X-ray absorption spectroscopy and scanning transmission electron microscopy revealed the existence of bimetallic RuNi species, whereas density-functional theory calculations suggested Ni-doped Ru substantially decreased the Ea of C?H bond dissociation of lactate alkoxide to form pyruvate, which is the rate-determining step. The catalytic route established in this work creates new opportunities for glycerol utilization and enriches the substrate scope of renewable feedstock to access value-added amino acids.
Wang, Yunzhu,Furukawa, Shinya,Song, Song,He, Qian,Asakura, Hiroyuki,Yan, Ning
supporting information
p. 2289 - 2293
(2020/01/08)

Direct Synthesis of Free α-Amino Acids by Telescoping Three-Step Process from 1,2-Diols
A practical telescoping three-step process for the syntheses of α-amino acids from the corresponding 1,2-diols has been developed. This process enables the direct synthesis of free α-amino acids without any protection/deprotection step. This method was also effective for the preparation of a 15N-labeled α-amino acid. 1,2-Diols bearing α,β-unsaturated ester moieties afforded bicyclic α-amino acids through intramolecular [3 + 2] cycloadditions. A preliminary study suggests that the resultant α-amino acids are resolvable by aminoacylases with almost complete selectivity.
Inada, Haruki,Shibuya, Masatoshi,Yamamoto, Yoshihiko
supporting information
p. 709 - 713
(2019/01/25)

Electrosynthesis of amino acids from biomass-derivable acids on titanium dioxide
Seven amino acids were electrochemically synthesized from biomass-derivable α-keto acids and NH2OH with faradaic efficiencies (FEs) of 77-99% using an earth-Abundant TiO2 catalyst. Furthermore, we newly constructed a flow-Type electrochemical reactor, named a "polymer electrolyte amino acid electrosynthesis cell", and achieved continuous production of alanine with an FE of 77%.
Fukushima, Takashi,Yamauchi, Miho
supporting information
p. 14721 - 14724
(2019/12/24)

METHOD FOR PRODUCING alpha-AMINO ACID
The present invention relates to a method for producing a specified α-amino acid, the method including allowing a specified α-amino acid amide and water to react with each other in the presence of a zirconium compound which contains zirconium and at least one metal element selected from the group consisting of lithium, nickel, copper, zinc, cesium, barium, hafnium, tantalum, cerium, and dysprosium.
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Paragraph 0157-0160

(2019/06/24)

DEHYDRATION AND AMINATION OF ALPHA-, BETA-DIHYDROXY CARBONYL COMPOUNDS TO ALPHA-AMINO ACIDS
Processes are disclosed for synthesizing an α-amino acid or α-amino acid derivative, from a starting compound having a carbonyl functional group (C=O), with hydroxy-substituted carbon atoms at alpha (α) and beta (β) positions, relative to the carbonyl functional group. An α-, β-dihydroxy carboxylic acid or carboxylate is dehydrated to form a dicarbonyl intermediate by transformation of the α-hydroxy group to a second carbonyl group (adjacent a carbonyl group of the starting compound) and removal of the β-hydroxy group. This dicarbonyl intermediate is optionally cracked to form a second dicarbonyl intermediate having fewer carbon atoms but preserving the first and second carbonyl groups. Either or both of the dicarbonyl intermediate and the cracked dicarbonyl intermediate are then reductively aminated.
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Paragraph 55

(2019/11/04)

ANTI-HUMAN PAPILLOMAVIRUS (HPV) ANTIGEN-BINDING PROTEINS AND METHODS OF USE THEREOF
The present invention provides antigen-binding proteins that specifically bind to an HLA-displayed human papillomavirus (HPV) peptide, and therapeutic and diagnostic methods of using those binding proteins.
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(2019/01/15)

The identification and use of robust transaminases from a domestic drain metagenome
Transaminases remain one of the most promising biocatalysts for use in chiral amine synthesis, however their industrial implementation has been hampered by their general instability towards, for example, high amine donor concentrations and organic solvent content. Herein we describe the identification, cloning and screening of 29 novel transaminases from a household drain metagenome. The most promising enzymes were fully characterised and the effects of pH, temperature, amine donor concentration and co-solvent determined. Several enzymes demonstrated good substrate tolerance as well as an unprecedented robustness for a wild-type transaminase. One enzyme in particular readily accepted IPA as an amine donor giving the same conversion with 2-50 equivalents, as well as being tolerant to a number of co-solvents, and operational in up to 50% DMSO-a characteristic as yet unobserved in a wild-type transaminase. This work highlights the value of using metagenomics for biocatalyst discovery from niche environments, and here has led to the identification of one of the most robust native transaminases described to date, with respect to IPA and DMSO tolerance.
Leipold, Leona,Dobrijevic, Dragana,Jeffries, Jack W.E.,Bawn, Maria,Moody, Thomas S.,Ward, John M.,Hailes, Helen C.
p. 75 - 86
(2019/01/11)

Organocatalytic Enantioselective Addition of α-Aminoalkyl Radicals to Isoquinolines
With a dual organocatalytic system involving a chiral phosphoric acid and a dicyanopyrazine-derived chromophore (DPZ) photosensitizer and under the irradiation with visible light, an enantioselective Minisci-type addition of α-amino acid-derived redox-active esters (RAEs) to isoquinolines has been developed. A variety of prochiral α-aminoalkyl radicals generated from RAEs were successfully introduced on isoquinolines, providing a range of valuable α-isoquinoline-substituted chiral secondary amines in high yields with good to excellent enantioselectivities.
Liu, Xiangyuan,Liu, Yang,Chai, Guobi,Qiao, Baokun,Zhao, Xiaowei,Jiang, Zhiyong
supporting information
p. 6298 - 6301
(2018/10/09)

Sustainable synthesis of amino acids by catalytic fixation of molecular dinitrogen and carbon dioxide
The industrial process of nitrogen fixation is complex and results in a huge economic and environmental impact. It requires a catalyst and high temperature and pressure to induce the rupture of the strong N-N bond and subsequent hydrogenation. On the other hand, carbon dioxide removal from the atmosphere has become a priority objective due to the high amount of global carbon dioxide emissions (i.e. 36 200 million tons in 2015). In this work, we fix nitrogen from N2 and carbon from CO2 and CH4 to obtain both glycine and alanine (d/l racemic mixture), the two simplest amino acids. The synthesis, catalyzed by polarized hydroxyapatite under UV light irradiation and conducted in an inert reaction chamber, starts from a simple gas mixture containing N2, CO2, CH4 and H2O and uses mild reaction conditions. At atmospheric pressure and 95 °C, the glycine and alanine molar yields with respect to CH4 or CO2 are about 1.9% and 1.6%, respectively, but they grow to 3.4% and 2.4%, when the pressure increases to 6 bar and the temperature is maintained at 95 °C. Besides, the minimum temperature required for the successful production of detectable amounts of amino acids is 75 °C. Accordingly, an artificial photosynthetic process has been developed by using an electrophotocatalyst based on hydroxyapatite thermally and electrically stimulated and coated with zirconyl chloride and a phosphonate. The synthesis of amino acids by direct fixation of nitrogen and carbon from gas mixtures opens new avenues regarding the nitrogen fixation for industrial purposes and the recycling of carbon dioxide.
Rivas, Manuel,Del Valle, Luís J.,Turon, Pau,Alemán, Carlos,Puiggalí, Jordi
supporting information
p. 685 - 693
(2018/02/14)

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)

Metal-induced supramolecular chirality inversion of small self-assembled molecules in solution
A non-covalent self-assembled chiral alanyl aminopyridine ligand exhibits supramolecular chirality in solution, independent of the organic solvent used. The supramolecular chirality of the assemblies is completely inverted by complexation to zinc ions. To date, such a supramolecular metal-ligand system has not been reported in the literature.
Kokan, Zoran,Peri?, Berislav,Vazdar, Mario,Marini?, ?eljko,Viki?-Topi?, Dra?en,Me?trovi?, Ernest,Kirin, Sre?ko I.
supporting information
p. 1945 - 1948
(2017/02/15)

Degradation of complexons derived from succinic acid under UV radiation
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
p. 507 - 511
(2017/08/02)

General Synthesis of Amino Acid Salts from Amino Alcohols and Basic Water Liberating H2
An atom-economical and environmentally friendly method to transform amino alcohols to amino acid salts using just basic water, without the need of pre-protection or added oxidant, catalyzed by a ruthenium pincer complex, is developed. Water is the solvent, the source of the oxygen atom of the carboxylic acid group, and the actual oxidant, with liberation of dihydrogen. Many important and useful natural and unnatural amino acid salts can be produced in excellent yields by applying this new method.
Hu, Peng,Ben-David, Yehoshoa,Milstein, David
supporting information
p. 6143 - 6146
(2016/06/09)

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)

NMR study of the composition of aqueous 2-aminoethanol solution used for absorption of carbon dioxide from fuel gases
The compositions of aqueous 2-aminoethanol solutions used in industry for absorption of carbon dioxide resulting from combustion of natural gas have been determined by1H and13C NMR spectroscopy. The absorption process does not involve generally accepted paths of thermal decomposition of the absorbent in the reaction with carbon dioxide, but the main path is non-oxidative decomposition of 2-aminoethanol into ammonia and ethylene oxide. Splitting of the NMR signals of carbamate anion formed by reaction of 2-aminoethanol with carbon dioxide has been rationalized by specific structure of the anion due to intramolecular hydrogen bonding.
Talzi
p. 927 - 931
(2016/09/04)

ω-Transaminases for the amination of functionalised cyclic ketones
The potential of a number of enantiocomplementary ω-transaminases (ω-TAms) in the amination of cyclic ketones has been investigated. After a preliminary screening of several compounds with increasing complexity, different approaches to shift the equilibrium of the reaction to the amine products were studied, and reaction conditions (temperature and pH) optimised. Interestingly, 2-propylamine as an amine donor was tolerated by all five selected ω-TAms, and therefore used in further experiments. Due to the higher conversions observed and interest in chiral amines studies then focused on the amination of α-tetralone and 2-methylcyclohexanone. Both ketones were aminated to give the corresponding amine with at least one of the employed enzymes. Moreover, the amination of 2-methylcyclohexanone was investigated in more detail due to the different stereoselectivities observed with TAms used. The highest yields and stereoselectivities were obtained using the ω-TAm from Chromobacterium violaceum (CV-TAm), producing 2-methylcyclohexylamine with complete stereoselectivity at the (1S)-amine position and up to 24 : 1 selectivity for the cis : trans [(1S,2R) : (1S,2S)] isomer.
Richter,Simon,Lechner,Kroutil,Ward,Hailes
p. 8843 - 8851
(2015/08/24)

Biocatalytic asymmetric synthesis of unnatural amino acids through the cascade transfer of amino groups from primary amines onto keto acids
Flee to the hills: An unfavorable equilibrium in the amino group transfer between amino acids and keto acids catalyzed by α-transaminases was successfully overcome by coupling with a ω-transaminase reaction as an equilibrium shifter, leading to efficient asymmetric synthesis of diverse unnatural amino acids, including L-tert-leucine and D-phenylglycine. Copyright
Park, Eul-Soo,Dong, Joo-Young,Shin, Jong-Shik
p. 3538 - 3542
(2014/01/06)

Racemization of the aspartic acid residue of amyloid-β peptide by a radical reaction
Human amyloid-β peptide 1-42 (Aβ) was subjected to a radical reaction by using ascorbic acid and CuCl2. The percentage of D-aspartic acid (D-Asp) after 24 h had increased to 6.69 ± 0.09%, this being comparable with the reported D-Asp concentration of purified core amyloids in Alzheimer's disease patients. This racemization was significantly inhibited by radical scavengers. L-Alanine was also racemized during the same reaction.
Tambo, Koharu,Yamaguchi, Tomomi,Kobayashi, Keiko,Terauchi, Eri,Ichi, Ikuyo,Kojo, Shosuke
p. 416 - 418
(2013/05/22)

Hydroxylamine as an oxygen nucleophile: Substitution of sulfonamide by a hydroxyl group in benzothiazole-2-sulfonamides
Benzothiazole-2-sulfonamides react with an excess of hydroxylamine in aqueous solutions to form 2-hydroxybenzothiazole, sulfur dioxide, and the corresponding amine. Mechanistic studies that employ a combination of structure-reactivity relationships, oxygen labeling experiments, and (in)direct detection of intermediates and products reveal that the reaction proceeds via oxygen attack, and that oxygen incorporated in the 2-hydroxybenzothiazole product derives from hydroxylamine. The reaction, which is performed under mild conditions, can be used as a deprotection method for cleavage of benzothiazole-2-sulfonyl-protected amino acids.
Kamps, Jos J. A. G.,Belle, Roman,Mecinovi?, Jasmin
supporting information
p. 1103 - 1108
(2013/03/28)

Meteorites as catalysts for prebiotic chemistry
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)

Lysine racemase from a lactic acid bacterium, Oenococcus oeni: Structural basis of substrate specificity
Oenococcus oeni, a lactic acid bacterium, possesses a lysine racemase, which has a specific activity towards basic amino acids. A comparison of amino acid residues around the active site suggested that Ile222 and Tyr354 of the Geobacillus stearothermophilus alanine racemase, which shares 60% sequence similarity with lysine racemase, were replaced by Thr224 and Trp355 in the O. oeni lysine racemase. T224I/W355Y double mutations significantly decreased the activity of lysine racemase, whereas I222T/Y354W double mutations endowed alanine racemase with lysine racemization activity. These results suggest that the two residues play an important role in lysine racemization.
Kato, Shiro,Hemmi, Hisashi,Yoshimura, Tohru
p. 505 - 508
(2013/02/25)

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
supporting information; experimental part
p. 2146 - 2148
(2012/03/26)

Convenient method for reduction of C-N double bonds in oximes, imines, and hydrazones using sodium Borohydride-Raney ni system
(Chemical Equation Presented) A practical method has been developed for reduction of C-N double bond in oximes, imines, and hydrazones with sodium borohydride catalyzed by Raney Ni. The reactions were carried out in basic aqueous solution, and the desired products were obtained in moderate yields after a simple procedure. This method can be applied to synthesize simpler aliphatic or aromatic amines and its analogs. Copyright Taylor & Francis Group, LLC.
Yang, Yihua,Liu, Shouxin,Li, Junzhang,Tian, Xia,Zhen, Xiaoli,Han, Jianrong
experimental part
p. 2540 - 2554
(2012/07/27)

Conductometric method for the rapid characterization of the substrate specificity of amine-transaminases
Amine-transaminases (ATAs, ω-transaminases, ω-TA) are PLP-dependent enzymes that catalyze amino group transfer reactions. In contrast to the widespread and wellknown amino acid-transaminases, ATAs are able to convert substrates lacking an a-carboxylic functional group. They have gained increased attention because of their potential for the asymmetric synthesis of optically active amines, which are frequently used as building blocks for the preparation of numerous pharmaceuticals. Having already introduced a fast kinetic assay based on the conversion of the model substrate α-methylbenzylamine for the characterization of the amino acceptor specificity, we now report on a kinetic conductivity assay for investigating the amino donor specificity of a given ATA. The course of an ATA-catalyzed reaction can be followed conductometrically since the conducting substrates, a positively charged amine and a negatively charged keto acid, are converted to nonconducting products, a noncharged ketone and a zwitterionic amino acid. The decrease of conductivity for the investigated reaction systems were determined to be 33-52 μS mM-1. In contrast to other ATA-assays previously described, with this approach all transamination reactions between any amine and any keto add can be monitored without the need for an additional enzyme or staining solutions. The assay was used for the characterization of a ATA from Rhodobacter sphaeroides, and the data obtained were in excellent agreement with gas chromatography analysis.
Schaetzle, Sebastian,Hoehne, Matthias,Robins, Karen,Bornscheuer, Uwe T.
body text
p. 2082 - 2086
(2010/08/20)

Biocatalytic access to α,α-dialkyl-α-amino acids by a mechanism-based approach
(figure presented) New donors - new products: Threonine aldolases (L-TA, D-TA) have now been found to accept donors other than glycine. In a simple asymmetric biocatalytic aldol reaction alanine, serine, and cysteine reacted with a range of simple acceptor aldehydes to yielded α-substituted serine derivatives (see scheme; PLP=pyridoxal phosphate).
Fesko, Kateryna,Uhl, Michael,Steinreiber, Johannes,Gruber, Karl,Griengl, Herfried
supporting information; experimental part
p. 121 - 124
(2010/04/04)

A new acylamidase from Rhodococcus erythropolis TA37 can hydrolyze N-substituted amides
A new acylamidase was isolated from Rhodococcus erythropolis TA37 and characterized. N-Substituted acrylamides (isopropyl acrylamide, N,N-dimethyl-aminopropyl acrylamide, and methylene-bis-acrylamide), acid para-nitroanilides (4′-nitroacetanilide, Gly-pNA, Ala-pNA, Leu-pNA), and N-acetyl derivatives of glycine, alanine, and leucine are good substrates for this enzyme. Aliphatic amides (acetamide, acrylamide, isobutyramide, n-butyramide, and valeramide) are also used as substrates but with less efficiency. The enzyme subunit mass by SDS-PAGE is 55 kDa. Maximal activity is exhibited at pH 7-8 and 55°C. The enzyme is stable for 15 h at 22°C and for 0.5 h at 45°C. The Michaelis constant (K m) is 0.25 mM with Gly-pNA and 0.55 mM with Ala-pNA. The acylamidase activity is suppressed by inhibitors of serine proteases (phenylmethylsulfonyl fluoride and diisopropyl fluorophosphate) but is not suppressed by inhibitors of aliphatic amidases (acetaldehyde and nitrophenyl disulfides). The N-terminal amino acid sequence of the acylamidase is highly homologous to those of two putative amidases detected from sequenced R. erythropolis genomes. It is suggested that the acylamidase together with the detected homologs forms a new class within the amidase signature family.
Lavrov,Zalunin,Kotlova,Yanenko
experimental part
p. 1006 - 1013
(2011/11/06)

Synthesis of α-amino and α-hydroxy acids under volcanic conditions: implications for the origin of life
Facile synthesis of α-hydroxy and α-amino acids is observed at temperatures from 145 to 280 °C with catalytic Ni2+, with cyano ligands as source for C and N, and with CO as a reductant and as a source for C. Implications for the problem of the origin of life are discussed.
Huber, Claudia,Eisenreich, Wolfgang,W?chtersh?user, Günter
scheme or table
p. 1069 - 1071
(2010/04/05)

Synthesis and characterization of new bis-symmetrical adipoyl, terepthaloyl, chiral diimido-di-L-alanine diesters and chiral phthaloyl-L-alanine ester of tripropoxy p-tert-butyl calix[4]arene and study of their hosting ability for alanine and Na+
Bis-symmetrical tripropoxy p-tert-butyl calix[4]arene esters were prepared from the reaction of tripropoxy calix[4]arene (1HFr3) with di-acyl chlorides as bridges in the presence of sodium hydride. The esters, which were synthesized from L-alanine acyl chloride derivatives, are optically active. In all of these esters, calix[4]arene cavities have a pinched cone conformation. The structures of these esters were confirmed by FT-IR, 1H NMR and 13C NMR spectroscopy, elemental analysis and ion positive FAB mass spectrometry.
Nasuhi Pur,Akbari Dilmaghani
experimental part
p. 25 - 30
(2011/07/31)

High rates and substrate selectivities in water by polyvinylimidazoles as transaminase enzyme mimics with hydrophobically bound pyridoxamine derivatives as coenzyme mimics
(Chemical Equation Presented) Free-radical polymers of 4-vinylimidazole and copolymers with 1-dodecyl-4-vinylimidazole were used as enzyme mimics to transaminate pyruvic acid to alanine, phenylpyruvic acid to phenylalanine, and indole-3-pyruvic acid to tryptophan in water at pH 7.5 and 20 °C using pyridoxamines carrying hydrophobic side chains as coenzyme mimics. The best enzyme mimic accelerated the transamination of indole-3-pyruvic acid by a factor of 4 million relative to the rate without the polymer, a higher rate ratio than we had previously achieved with a polyaziridine-based enzyme mimic. The properties of various polyvinylimidazoles were compared, including those prepared with the RAFT modification of the polymerization process.
Skouta, Rachid,Wei, Sujun,Breslow, Ronald
supporting information; experimental part
p. 15604 - 15605
(2010/01/30)

METHOD FOR SYNTHESIS OF KETO ACID OR AMINO ACID BY HYDRATION OF ACETHYLENE COMPOUND
An object of the present invention is to provide a method for synthesis of keto acids by hydration of an acetylene compound (acetylene-carboxylic acids) under mild conditions free from harmful mercury catalysts and a method for synthesis of amino acids from acetylene-carboxylic acids in a single container (one-pot or tandem synthesis). In one embodiment of the method according to the present invention for synthesis of keto acids, acetylene-carboxylic acids is hydrated in the presence of a metal salt represented by General Formula (1), where M1 represents an element in Group VIII, IX, or X of the periodic table, and X1, X2, or X3 ligand represents halogen, H2O, or a solvent molecule, and k represents a valence of a cation species, and Y represents an anion species, and L represents a valence of the anion species, and each of K and L independently represents 1 or 2, and k × m = L × n.
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Page/Page column 25; 26; 27

(2008/12/06)

Compositions, kits, and methods relating to the human FEZ1 gene, a novel tumor suppressor gene
The invention relates to isolated polynucleotides homologous with a portion of one strand of the human tumor suppressor gene, FEZ1, and to the tumor suppressor protein encoded thereby, Fez1. The polynucleotides are useful, for example, as probes, primers, portions of expression vectors, and the like. The invention also includes diagnostic, therapeutic, cell proliferation enhancement, and screening methods which involve these polynucleotides and protein. The invention further includes kits useful for performing the methods of the invention.
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(2008/06/13)

Chemical effects of anodic contact glow discharge electrolysis: Formation of amino acid
In Contact Glow Discharge Electrolysis (CGDE), a plasma is sustained by d.c. glow discharges between an electrode and the electrolyte around it. The chemical results of CGDE are significantly non faradaic. With the anodic plasma in an aqueous electrolyte, non-faradaic results originate mainly from break-up of liquid water molecules near the plasma | anolyte interface by sufficiently energized H2Ogas+ ions coming out of the plasma into H? and OH? in yields as high as 13 moles per mol electron of electricity. The radical generating potentiality of anodic CGDE in high local concentration in liquid phase has been explored as a tool for synthesizing amino acids from ammoniacal solution of carboxylates. The results show that amino acids such as glycine from ammoniacal acetate electrolyte and α-alanine from ammoniacal propionate electrolyte are formed in yields exceeding the Faraday law value. The formation of amino acid by anodic CGDE has been explained by radical scavenging action of ammonia and carboxylates on H? and OH? radicals and by mutual interaction between ?NH2 and RC?HCOO- radicals formed. The present technique requires 0.1-0.2 kcal for production of 10-5 mol of glycine as compared to 24 kcal by spark discharge and 50 kcal by X-ray for glycine production from constituents of reducing atmosphere.
Sengupta,Srivastava, Monika
p. 787 - 791
(2007/10/03)

Stereoselectivity and expanded substrate scope of an engineered PLP-dependent aldolase
Optimizing the active site: A pyridoxal 5′-phosphate(PLP)-dependent alanine racemase was converted into a retro-aldolase by a single active-site mutation. This new catalyst reacts efficiently with quaternary β-hydroxy α-amino acids, a class of molecules that natural aldolases have not been evolved to handle. Computational docking experiments suggest a novel mechanism for this process and rationalize the stereochemical preferences of the enzyme. (Chemical Equation Presented).
Seebeck, Florian P.,Guainazzi, Angelo,Amoreira, Celine,Baldridge, Kim K.,Hilvert, Donald
p. 6824 - 6826
(2007/10/03)

Method for producing amines by homogeneously catalyzed reductive amination of carbonyl compounds
The invention relates to the preparation of chiral or achiral amines by reaction of aldehydes or ketones with ammonia or primary or secondary amines in the presence of hydrogen and in the presence of homogeneous metal catalysts under mild conditions. Metal catalysts which can be used are complexes of late transition metals with chiral or achiral phosphorus-containing ligands.
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Page/Page column 14

(2010/02/11)

Synthetic method for amino acid using the water of high temperature and high pressure
PROBLEM TO BE SOLVED: To provide a method for synthesizing a prescribed amino acid by the high temperature and high pressure reaction. SOLUTION: The substitution reaction is occured and the aimed amino acid (for example, alanine) can be synthesized, by means of giving the high temperature and high pressure water reaction (for example, 240 C and 30 sec), under the condition where the both raw materials of the oxo acid (for example, pyruvic acid) and the amino acid (for example, glycine) exist at the same time. Moreover, the yield of the amino acid can be improved by adjusting the pH of the solution to lower one, before this high temperature and high pressure water reaction is given..
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Page/Page column 13

(2008/06/13)

Amino acid derivatives and sweetening agent
Novel amino acid derivatives (including ones in the form of a salt) such as 2-amino-4-hydroxy-4-ethylcarbamoyl-4-(3-indolylmethyl)butyric acid are provided which can be used as a low-calorie sweetening agent that is excellent in a degree of sweetness, and as an efficient ingredient thereof. These substances can be used as an efficient ingredient of a sweetening agent, and also, can be used for imparting sweetness to products such as beverages and foods requiring sweetness. Therefore, such excellent sweetening agents, and foods or beverages to which sweetness is imparted can be also provided.
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Page/Page column 8-9

(2010/02/11)

Transamination reactions with multiple turnovers catalyzed by hydrophobic pyridoxamine cofactors in the presence of polyethylenimine polymers
Pyridoxamines carrying hydrophobic side chains reversibly bind into the hydrophobic core of polyethylenimines and transaminate ketoacids to amino acids with as much as a 725000-fold rate acceleration. Turnover catalysis was achieved by sacrificial oxidative decarboxylation of C-substituted amino acids, which reconverted the pyridoxals to pyridoxamines. Copyright
Liu, Lei,Zhou, Wenjun,Chruma, Jason,Breslow, Ronald
p. 8136 - 8137
(2007/10/03)

T-CELL SELECTIVE INTERLEUKIN-4 AGONISTS
The invention is directed to human IL-4 muteins numbered in accordance with wild-type IL-4 having T-cell activating activity, but having reduced endothelial cell activating activity. In particular, the invention is related to human IL-4 muteins wherein the surface-exposed residues of the D helix of the wild-type IL-4 are mutated whereby the resulting mutein causes T-cell proliferation, and causes reduced IL-6 secretion from HUVECs, relative to wild-type IL-4. This invention realizes a less toxic IL-4 mutant that allows greater therapeutic use of this interleukin. Further, the invention is directed to IL-4 muteins having single, double and triple mutations represented by the designators R121A, R121D, R121E, R121F, R121H, R121I, R121K, R121N, R121P, R121T, R121W; Y124A, Y124Q, Y124R, Y124S, Y124T; Y124A/S125A, T13D/R121E; and R121T/E122F/Y124Q, when numbered in accordance with wild-type IL-4 (His=1). The invention also includes polynucleotides coding for the muteins of the invention, vectors containing the polynucleotides, transformed host cells, pharmaceutical compositions comprising the muteins, and therapeutic methods of treatment.
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(2008/06/13)

Synthetic receptors
The invention is directed to synthetic receptor(s) which comprises a polyfunctional organic template covalently linked to two or more oligomers which may independently be the same or different and may independently be straight chain, cyclic or branched. The template may be linked to an identifier which uniquely defines the synthetic receptor. The identifier is a stable chemical molecule or a plurality of stable chemical molecules distinguishable and detectable to picomolar levels or may be an oligonucleotide. In a preferred embodiment, the template is covalently linked to a solid support which is linked to an identifier. In addition, the invention includes methods of preparing synthetic receptors and synthetic receptor libraries. The synthetic library may be linked with identifiers such that the library comprises a plurality of different synthetic receptor members. The invention also provides methods for assaying a synthetic receptor library to determine suitable synthetic receptor(s) which (a) bind an acceptor molecule; (b) exhibit biological activity; (c) which catalyze a reaction or inhibit a catalyzed reaction; and (d) separate compounds in chromatography.
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(2008/06/13)

pH-Dependent Chemoselective Synthesis of α-Amino Acids. Reductive Amination of α-Keto Acids with Ammonia Catalyzed by Acid-Stable Iridium Hydride Complexes in Water
An acid-stable hydride complex [Cp*IrIII(bpy)H]+ {1, Cp* = η5-C5Me5, bpy = 2,2′-bipyridine} serves as the active catalyst for the highly chemoselective synthesis of α-amino acids by reductive aminatio
Ogo, Seiji,Uehara, Keiji,Abura, Tsutomu,Fukuzumi, Shunichi
p. 3020 - 3021
(2007/10/03)

Asymmetric synthesis of amino acids by Cr(II) complexes of natural amino acids
Stoichiometric reduction of the C,N double bond of oxime precursors of α-amino acids was performed in aqueous media by Cr(II) complexes of natural amino acids. The reduction of oximes of α-ketophenylacetic, α-keto-β-phenylpropionic and α-ketopropionic acids proceeded up to >90% conversion and 2-30% enantiomeric excess. 1:2 complexes of Cr(II) with l-alanine, l-valine, l-aspartic acid, l-histidine and l-phenylalanine were used as reducing agents. The reduction of α-(oximino)phenylacetic acid showed increasing e.e. (and decreasing conversion) with increasing temperature.
Micskei, Károly,Holczknecht, Orsolya,Hajdu, Csongor,Patonay, Tamás,Marchis, Valér,Meo, Milena,Zucchi, Claudia,Pályi, Gyula
p. 143 - 148
(2007/10/03)