PMID: 3759971Oct 15, 1986Paper

S-adenosylhomocysteinase from rat liver. Amino acid sequences of the peptides containing active site cysteine residues modified by treatment with 5'-p-fluorosulfonylbenzoyladenosine.

The Journal of Biological Chemistry
T GomiM Fujioka

Abstract

5'-p-Fluorosulfonylbenzoyladenosine (FSBA) inactivates rat liver S-adenosylhomocysteinase exhibiting characteristics of an active site-directed reagent. The inactivation is not associated with the covalent binding of the reagent, but is correlated with the loss of 2 sulfhydryl groups/enzyme subunit (Takata, Y., and Fujioka, M. (1984) Biochemistry 23, 4357-4362). Treatment of the FSBA-inactivated enzyme with iodoacetate in the absence of reducing agent and then with [14C] iodoacetate after reduction with 2-mercaptoethanol yielded the enzyme containing approximately 2 mol of radiolabeled S-carboxymethylcysteine/mol of subunit. Analysis of tryptic peptides showed that the radioactivity was associated with 2 carboxymethylcysteine-containing peptides whose amino acid sequences were: Trp-Ser-Ser-Cys(Cm)-Asn-Ile-Phe-Ser-Thr-Gln-Asp-His-Ala-Ala-Ala-Ala-Ile- Ala-Lys and Gly-Glu-Thr-Asp-Glu-Glu-Tyr-Leu-Trp-Cys(Cm)-Ile-Glu-Gln-Thr-Leu-His-Phe- Lys, respectively. These results indicate that the inactivation of S-adenosylhomocysteinase by FSBA is the consequence of formation of a disulfide between two specific cysteine residues on each of the four identical subunits.

Related Concepts

Related Feeds

ASBMB Publications

The American Society for Biochemistry and Molecular Biology (ASBMB) includes the Journal of Biological Chemistry, Molecular & Cellular Proteomics, and the Journal of Lipid Research. Discover the latest research from ASBMB here.