|
Sofia A. Shilova, Tatiana V. Rakitina, Vladimir O. Popov, Ekaterina Yu. Bezsudnova
Prospects of application of D-amino acid
transaminase from Aminobacterium colombiense for (R)-selective amination of α-ketoacids
Abstract
Abstract. D-amino
acid transaminase from Aminobacterium colombiense was applied for (R)-selective
amination of 2-oxobutyrate, 2-oxovalerate and 2-oxo-4-phenylbutyrate to produce
unnatural D-amino acids – D-homoalanine, D-norvaline and D-homophenylalanine.
To increase the product yield of D-amino acids, a one-pot three-enzyme system
was developed. The system included transaminase from A. colombiense, (R)-2-hydroxyglutarate
dehydrogenase and glucose dehydrogenase and effectively shifted the equilibrium
of transamination reaction toward the products. The system functioned in both neutral and slightly alkaline
pH. We found that at high substrate concentrations (500 mM) transaminase from A.
colombiense was inhibited by the products accumulated in the system. The
optimization of operational conditions of the three-enzyme system led to the
following yields of the target products: 435 mM D-homoalanine, 320 mM
D-norvaline and 47,5 mM
D-homophenylalanine; the enantiomeric excess of produced D-amino acids exceeded
99,5%.
Key words: biocatalysis,
(R)-selective amination, three-enzyme system, D-amino acid transaminases
Copyright (C) Chemistry Dept., Moscow State University, 2002
|
|
