Enantioselective Reductive Amination of α-Keto Acids to α-Amino Acids by a Pyridoxamine Cofactor in a Protein Cavity

1996 ◽  
Vol 118 (44) ◽  
pp. 10702-10706 ◽  
Author(s):  
Hao Kuang ◽  
Matthew L. Brown ◽  
Ronald R. Davies ◽  
Eva C. Young ◽  
Mark D. Distefano
Keyword(s):  
Amino Acids ◽  
Reductive Amination ◽  
Keto Acids ◽  
Protein Cavity

Development of β-Amino Acid Dehydrogenase for the Synthesis of β-Amino Acids via Reductive Amination of β-Keto Acids

ACS Catalysis ◽  
2015 ◽  
Vol 5 (4) ◽  
pp. 2220-2224 ◽  
Author(s):  
Dalong Zhang ◽  
Xi Chen ◽  
Rui Zhang ◽  
Peiyuan Yao ◽  
Qiaqing Wu ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Reductive Amination ◽  
Acid Dehydrogenase ◽  
Amino Acid Dehydrogenase ◽  
Keto Acids

scholarly journals Electrochemical Molecular Conversion of α-Keto Acid to Amino Acid at a Low Overpotential Using a Nanoporous Gold Catalyst

2021 ◽  
Vol 22 (17) ◽  
pp. 9442
Author(s):  
Yasuhiro Mie ◽  
Shizuka Katagai ◽  
Chitose Mikami
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Gold Electrode ◽  
Reductive Amination ◽  
Gold Catalyst ◽  
Nanoporous Gold ◽  
Keto Acid ◽  
Applied Potential ◽  
Keto Acids ◽  
Optimized Conditions

A nanoporous gold (NPG) electrode prepared through a facile anodization technique was employed in the electrochemical reductive amination of biomass-derivable α-keto acids in the presence of a nitrogen source to produce the corresponding amino acids. NPG showed a clear reductive current in the presence of α-keto acid and NH2OH, and the electrolysis experiments confirmed the production of L-amino acid. A reductive voltammetric signal at the NPG electrode appeared at a more positive potential by 0.18–0.79 V, compared with those at the planar-gold electrode without anodization and other previously reported electrode systems, indicating the high activity of the prepared nanostructure for the electrochemical reaction. Maximum Faradaic efficiencies (FEs) of 74–93% in the reductive molecular conversion to amino acids of Ala, Asp, Glu, Gly, and Leu were obtained under the optimized conditions. The FE values were strongly dependent on the applied potential in the electrolysis, suggesting that the hydrogen evolution reaction at the electrode surface was more significant as the applied potential became more negative. The effect of potential at the NPG was lower than that at the planar-gold electrode. These results indicate that nanostructurization decreases the overpotential for the electrochemical reductive amination, resulting in high FE.

scholarly journals ω-Amino Acid:Pyruvate Transaminase from Alcaligenes denitrificans Y2k-2: a New Catalyst for Kinetic Resolution of β-Amino Acids and Amines

2004 ◽  
Vol 70 (4) ◽  
pp. 2529-2534 ◽  
Author(s):  
Hyungdon Yun ◽  
Seongyop Lim ◽  
Byung-Kwan Cho ◽  
Byung-Gee Kim
Keyword(s):  
Amino Acids ◽  
Kinetic Resolution ◽  
Specific Activity ◽  
Expression System ◽  
Enantiomeric Excess ◽  
Selective Enrichment ◽  
Alcaligenes Denitrificans ◽  
Keto Acids ◽  
Optically Pure ◽  
High Stereoselectivity

ABSTRACT Alcaligenes denitrificans Y2k-2 was obtained by selective enrichment followed by screening from soil samples, which showed ω-amino acid:pyruvate transaminase activity, to kinetically resolve aliphatic β-amino acid, and the corresponding structural gene (aptA) was cloned. The gene was functionally expressed in Escherichia coli BL21 by using an isopropyl-β-d-thiogalactopyranoside (IPTG)-inducible pET expression system (9.6 U/mg), and the recombinant AptA was purified to show a specific activity of 77.2 U/mg for l-β-amino-n-butyric acid (l-β-ABA). The enzyme converts various β-amino acids and amines to the corresponding β-keto acids and ketones by using pyruvate as an amine acceptor. The apparent Km and V max for l-β-ABA were 56 mM and 500 U/mg, respectively, in the presence of 10 mM pyruvate. In the presence of 10 mM l-β-ABA, the apparent Km and V max for pyruvate were 11 mM and 370 U/mg, respectively. The enzyme exhibits high stereoselectivity (E > 80) in the kinetic resolution of 50 mM d,l-β-ABA, producing optically pure d-β-ABA (99% enantiomeric excess) with 53% conversion.

Free Amino Acids in Citrullus vulgaris (Watermelon)

PEDIATRICS ◽  
1984 ◽  
Vol 73 (6) ◽  
pp. 879-879
Author(s):  
T. A. TEDESCO ◽  
S. A. BENFORD ◽  
R. C. FOSTER ◽  
L. A. BARNESS
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Neonatal Period ◽  
Essential Amino Acids ◽  
Solid Foods ◽  
Citrullus Vulgaris ◽  
Keto Acids ◽  
Wet Weight ◽  
Cycle Disorders

To the Editor.— Currently accepted dietary management of citrullinemia and other urea cycle disorders includes protein restriction, sodium benzoate, and dietary supplements of keto acids or essential amino acids with postblock intermediates such as arginine in citrullinemia and arginino-succinic aciduria. When a child survives the neonatal period on such a regimen and solid foods are introduced into the diet, there is at least one fruit that should be avoided, Citrullus Vulgaris, commonly known as watermelon. Quantitation of free amino acids extracted from 1 g wet weight of watermelon fruit yielded the following (in mmoles per gram wet weight): Phenylalanine, 1.25; histidine, 0.24; tryptophan, 0.35; lysine, 0.82; ornithine, 0.32; arginine, 11.36; aspartic acid, 0.97; threonine, 0.74; serine, 1.05; glutamine, 3.86; glutamic acid, 1.38; citrulline, 23.68; alanine, 1.15; valine, 0.17; isoleucine, 1.24; leucine, 0.24.

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