type	Journal Article
authors	Tomisawa, H.; Ichimoto, N.; Takanohashi, Y.; Ichihara, S.; Fukazawa, H.; Tateishi, M.
title	Purification and characterization of cysteine conjugate transaminases from rat liver
journal	Xenobiotica
Activity	2.6.1.75
sel	selected
ui	2852419
year	(1988)
volume	18
number	9
pages	1015-28
keywords	Animal
abstract	1. Soluble cysteine-conjugate alpha-ketoglutarate transaminase (CAT-I) was purified about 670-fold from rat liver cytosol using s-(p- bromophenyl)-L-cysteine as amino acid substrate. The enzyme preparation of the final step of purification showed a single band in polyacrylamide gel electrophoresis. CAT-I accounted for 64% of the transaminase activity in cytosol. 2. The mol. wt of the enzyme was about 64,000 as determined by gel filtration. Respective Km values for s-(p-bromophenyl)-L-cysteine and alpha-ketoglutaric acid were 1.0 and 1.3 mM in Tris-acetate buffer (pH 7.0). Aminooxyacetic acid, hydroxylamine, and KCN inhibited the enzyme activity. 3. In addition to CAT-I, two isozymes (CAT-IIA and CAT-IIB) were partially purified from rat liver cytosol. In respect of mol. wt, substrate specificity towards cysteine conjugates, and several other properties, CAT-IIA and CAT-IIB were very similar to CAT-I. However, differences were observed for these enzymes in the rate of reverse reaction (formation reaction of cysteine conjugates and alpha-ketoglutaric acid) and substrate specificity towards L-aspartic acid and L-cysteinesulphinic acid.
last changed	2009/05/19 16:04