H. Tomisawa, N. Ichimoto, S. Ichihara
Sep 1, 1988
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0
Influential Citations
13
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Journal
Xenobiotica; the fate of foreign compounds in biological systems
Abstract
1. Rat liver cystathionase [EC.4.4.1.1] mediated a cleavage reaction of the C-S bond of S-alkyl-L-cysteine conjugates to give equimolar amounts of corresponding thiols, ammonia, and pyruvic acid. Neither S-aryl- nor S-aralkyl-L-cysteine conjugates were acceptable substrates. 2. The Km value for S-(tert-butyl)-L-cysteine was 0.3 mM at pH 8.5 in Tris-HCl buffer. 3. The S-alkyl-L-cysteine lyase activity of cystathionase was inhibited with carbonyl reagents and dithiothreitol. 4. The present finding that cystathionase has activity towards cysteine conjugates may provide some insights into the role of this enzyme in the metabolism of xenobiotics.