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B6db references: 15606768

type Journal Article
authors Han, Q.; Li, J.; Li, J.
title pH dependence, substrate specificity and inhibition of human kynurenine aminotransferase I
journal Eur J Biochem
sel selected
ui 15606768
year (2004)
volume 271
number 23-24
pages 4804-14
keywords Aminotransferases/*metabolism
abstract Human kynurenine aminotransferase I/glutamine transaminase K (hKAT-I) is an important multifunctional enzyme. This study systematically studies the substrates of hKAT-I and reassesses the effects of pH, Tris, amino acids and alpha-keto acids on the activity of the enzyme. The experiments were comprised of functional expression of the hKAT-I in an insect cell/baculovirus expression system, purification of its recombinant protein, and functional characterization of the purified enzyme. This study demonstrates that hKAT-I can catalyze kynurenine to kynurenic acid under physiological pH conditions, indicates indo-3-pyruvate and cysteine as efficient inhibitors for hKAT-I, and also provides biochemical information about the substrate specificity and cosubstrate inhibition of the enzyme. hKAT-I is inhibited by Tris under physiological pH conditions, which explains why it has been concluded that the enzyme could not efficiently catalyze kynurenine transamination. Our findings provide a biochemical basis towards understanding the overall physiological role of hKAT-I in vivo and insight into controlling the levels of endogenous kynurenic acid through modulation of the enzyme in the human brain.
last changed 2009/02/16 13:06

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