302-72-7Relevant articles and documents
Rational engineering ofAcinetobacter tandoiiglutamate dehydrogenase for asymmetric synthesis ofl-homoalanine through biocatalytic cascades
Diao, Shiqing,Jiang, Shuiqin,Liu, Yan,Sun, Yangyang,Wang, Hualei,Wang, Liuzhu,Wei, Dongzhi
, p. 4208 - 4215 (2021/06/30)
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.
A Photoregulated Racemase Mimic
Saha, Monochura,Hossain, Munshi Sahid,Bandyopadhyay, Subhajit
supporting information, p. 5220 - 5224 (2021/01/18)
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.
Mechanistic insight into metal ion-catalyzed transamination
Mayer, Robert J.,Kaur, Harpreet,Rauscher, Sophia A.,Moran, Joseph
supporting information, p. 19099 - 19111 (2021/11/22)
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.
Biocatalysed synthesis of chiral amines: continuous colorimetric assays for mining amine-transaminases
Gourbeyre, Léa,Heuson, Egon,Charmantray, Franck,Hélaine, Virgil,Debard, Adrien,Petit, Jean-Louis,de Berardinis, Véronique,Gefflaut, Thierry
, p. 904 - 911 (2021/02/26)
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.
The Effect of Visible Light on the Catalytic Activity of PLP-Dependent Enzymes
Gerlach, Tim,Nugroho, David Limanhadi,Rother, D?rte
, p. 2398 - 2406 (2021/04/05)
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.
Synthesis of new amides based on N-Phthaloyl-α-Amino Acids
Tukhtaev,Yusupov,Vinogradova
, p. 3049 - 3058 (2021/05/28)
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.
Highly Efficient Synthesis of Amino Acids by Amination of Bio-Derived Hydroxy Acids with Ammonia over Ru Supported on N-Doped Carbon Nanotubes
Xie, Zhenbing,Chen, Bingfeng,Peng, Fangfang,Liu, Mingyang,Liu, Huizhen,Yang, Guanying,Han, Buxing
, p. 5683 - 5689 (2020/09/21)
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.
Scope and limitations of reductive amination catalyzed by half-sandwich iridium complexes under mild reaction conditions
Nguyen, Dat P.,Sladek, Rudolph N.,Do, Loi H.
supporting information, (2020/07/15)
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).
PERMANENTLY POLARIZED HYDROXYAPATITE, A PROCESS FOR ITS MANUFACTURE AND USES THEREOF
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Paragraph 0191-0199, (2020/07/04)
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.
Catalytic Production of Alanine from Waste Glycerol
Wang, Yunzhu,Furukawa, Shinya,Song, Song,He, Qian,Asakura, Hiroyuki,Yan, Ning
supporting information, p. 2289 - 2293 (2020/01/08)
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.
