RT Journal Article
SR Electronic
T1 Cysteine conjugate beta-lyase in the gastrointestinal bacterium Eubacterium limosum.
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 97
OP 103
VO 29
IS 1
A1 G L Larsen
A1 J L Stevens
YR 1986
UL http://molpharm.aspetjournals.org/content/29/1/97.abstract
AB A cysteine conjugate beta-lyase (beta-lyase) from the gastrointestinal bacterium Eubacterium limosum has been isolated and characterized. This organism has the highest specific activity for cysteine conjugate beta-lyase of the gastrointestinal bacteria studied. The beta-lyase was found to cleave the thioether linkage of S-alkyl- and S-aryl-L-cysteine conjugates. Stoichiometric amounts of 2-mercaptobenzothiazole, pyruvic acid, and ammonia were produced from the beta-lyase cleavage of S-(2-benzothiazolyl)-L-cysteine. The enzyme activity was inhibited by hydroxylamine, iodoacetic acid, or KCN. The enzyme appears to be a 75,000-Da dimer of two 38,000-Da subunits. A natural substrate, cystathionine, was cleaved by this enzyme, indicating that this beta-lyase has beta-cystathionase activity. These data suggest that a beta-cystathionase from E. limosum may be an important enzyme in the metabolism of a wide range of cysteine conjugates of xenobiotics to thiol-containing products.