type	Journal Article
authors	Yun, H.; Lim, S.; Cho, B.K.; Kim, B.G.
title	omega-Amino acid:pyruvate transaminase from Alcaligenes denitrificans Y2k-2: a new catalyst for kinetic resolution of beta-amino acids and amines
journal	Appl Environ Microbiol
Activity	2.6.1.18
Family	2.6.1.18.a
sel	selected
ui	15066855
year	(2004)
volume	70
number	4
pages	2529-34
abstract	Alcaligenes denitrificans Y2k-2 was obtained by selective enrichment followed by screening from soil samples, which showed omega-amino acid:pyruvate transaminase activity, to kinetically resolve aliphatic beta-amino acid, and the corresponding structural gene (aptA) was cloned. The gene was functionally expressed in Escherichia coli BL21 by using an isopropyl-beta-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-beta-amino-n-butyric acid (L-beta-ABA). The enzyme converts various beta-amino acids and amines to the corresponding beta-keto acids and ketones by using pyruvate as an amine acceptor. The apparent K(m) and V(max) for L-beta-ABA were 56 mM and 500 U/mg, respectively, in the presence of 10 mM pyruvate. In the presence of 10 mM L-beta-ABA, the apparent K(m) 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-beta-ABA, producing optically pure D-beta-ABA (99% enantiomeric excess) with 53% conversion.
last changed	2020/02/17 12:20