Enzymatic Preparation of ad-Amino Acid from a Racemic Amino Acid or Keto Acid

2008 ◽  
Vol 12 (6) ◽  
pp. 1119-1129 ◽  
Author(s):  
Ronald L. Hanson ◽  
Brian L. Davis ◽  
Steven L. Goldberg ◽  
Robert M. Johnston ◽  
William L. Parker ◽  
...  
Keyword(s):  
Amino Acid ◽  
Keto Acid ◽  
Enzymatic Preparation ◽  
Racemic Amino Acid

Enzymatic Preparation of an (S)-Amino Acid from a Racemic Amino Acid

2011 ◽  
Vol 15 (1) ◽  
pp. 241-248 ◽  
Author(s):  
Yijun Chen ◽  
Steven L. Goldberg ◽  
Ronald L. Hanson ◽  
William L. Parker ◽  
Iqbal Gill ◽  
...  
Keyword(s):  
Amino Acid ◽  
Enzymatic Preparation ◽  
Racemic Amino Acid

A new retro-aza-ene reaction: formal reductive amination of an α-keto acid to an α-amino acid

Tetrahedron ◽  
1992 ◽  
Vol 48 (9) ◽  
pp. 1715-1728 ◽  
Author(s):  
David B. Berkowitz ◽  
W. Bernd Schweizer
Keyword(s):  
Amino Acid ◽  
Reductive Amination ◽  
Keto Acid ◽  
Ene Reaction

scholarly journals Expression of a Heterologous Glutamate Dehydrogenase Gene inLactococcus lactis Highly Improves the Conversion of Amino Acids to Aroma Compounds

2000 ◽  
Vol 66 (4) ◽  
pp. 1354-1359 ◽  
Author(s):  
Liesbeth Rijnen ◽  
Pascal Courtin ◽  
Jean-Claude Gripon ◽  
Mireille Yvon
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Glutamate Dehydrogenase ◽  
Aroma Compounds ◽  
In Vitro Tests ◽  
Limiting Factor ◽  
Keto Acid ◽  
Cheese Curd ◽  
The Impact

ABSTRACT The first step of amino acid degradation in lactococci is a transamination, which requires an α-keto acid as the amino group acceptor. We have previously shown that the level of available α-keto acid in semihard cheese is the first limiting factor for conversion of amino acids to aroma compounds, since aroma formation is greatly enhanced by adding α-ketoglutarate to cheese curd. In this study we introduced a heterologous catabolic glutamate dehydrogenase (GDH) gene into Lactococcus lactis so that this organism could produce α-ketoglutarate from glutamate, which is present at high levels in cheese. Then we evaluated the impact of GDH activity on amino acid conversion in in vitro tests and in a cheese model by using radiolabeled amino acids as tracers. The GDH-producing lactococcal strain degraded amino acids without added α-ketoglutarate to the same extent that the wild-type strain degraded amino acids with added α-ketoglutarate. Interestingly, the GDH-producing lactococcal strain produced a higher proportion of carboxylic acids, which are major aroma compounds. Our results demonstrated that a GDH-producing lactococcal strain could be used instead of adding α-ketoglutarate to improve aroma development in cheese.

scholarly journals The case for regulating indispensable amino acid metabolism: the branched-chain α-keto acid dehydrogenase kinase-knockout mouse

2006 ◽  
Vol 400 (1) ◽  
Author(s):  
Susan M. Hutson
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Essential Amino Acids ◽  
The Body ◽  
Keto Acid ◽  
Acid Dehydrogenase ◽  
Indispensable Amino Acid ◽  
Branched Chain

BCAAs (branched-chain amino acids) are indispensable (essential) amino acids that are required for body protein synthesis. Indispensable amino acids cannot be synthesized by the body and must be acquired from the diet. The BCAA leucine provides hormone-like signals to tissues such as skeletal muscle, indicating overall nutrient sufficiency. BCAA metabolism provides an important transport system to move nitrogen throughout the body for the synthesis of dispensable (non-essential) amino acids, including the neurotransmitter glutamate in the central nervous system. BCAA metabolism is tightly regulated to maintain levels high enough to support these important functions, but at the same time excesses are prevented via stimulation of irreversible disposal pathways. It is well known from inborn errors of BCAA metabolism that dysregulation of the BCAA catabolic pathways that leads to excess BCAAs and their α-keto acid metabolites results in neural dysfunction. In this issue of Biochemical Journal, Joshi and colleagues have disrupted the murine BDK (branched-chain α-keto acid dehydrogenase kinase) gene. This enzyme serves as the brake on BCAA catabolism. The impaired growth and neurological abnormalities observed in this animal show conclusively the importance of tight regulation of indispensable amino acid metabolism.

Enantiomeric conversion of racemic amino acid mixtures via an oxidase-aminotransferase coupled system

1994 ◽  
Vol 35 (1) ◽  
pp. 29-32 ◽  
Author(s):  
Sapan A. Shah ◽  
Peter H. Schafer ◽  
Paul A. Recchia ◽  
Kevin J. Polach ◽  
David M. LeMaster
Keyword(s):  
Amino Acid ◽  
Coupled System ◽  
Amino Acid Mixtures ◽  
Racemic Amino Acid
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