title: Specificity of the reaction of rat liver L-serine dehydratase with aminothiols.
abstract: The degree, the mechanism, and the specificity of the inhibition of purified rat-liver L-serine dehydratase (EC 4.2.1.13) by L-cysteine and aminothiols have been investigated. All the aminothiols tested react with free pyridoxal-5'-phosphate (PLP); only L-cysteine reacts with PLP bound to the enzyme giving an absorption spectrum similar to that of the thiazolidinic ring formed in the chemical reaction. The reaction between L-cysteine and PLP bound to the enzyme has a particular behaviour, different from all the other aminothiols. A stereospecific interaction between L-cysteine and PLP bound to the enzyme, forming one of the two possible diastereoisomers, is postulated.
mesh_terms: D000818:Animals; D003545:Cysteine / Q000494:pharmacology*; D007700:Kinetics; D012695:L-Serine Dehydratase / Q000037:antagonists & inhibitors*; D008099:Liver / Q000201:enzymology*; D008297:Male; D011732:Pyridoxal Phosphate / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013053:Spectrophotometry; D013237:Stereoisomerism; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000494:pharmacology*
chemical_list: D013438:Sulfhydryl Compounds; D011732:Pyridoxal Phosphate; D012695:L-Serine Dehydratase; D003545:Cysteine