Localization of the sulfur-cyanolysis site of serum albumin to subdomain 3-AB.

The results of kinetic experiments measuring the effects of a variety of ligands on the sulfur-cyanolysis reaction catalyzed by serum albumin point to the conclusion that the active site for cyanolysis is on subdomain 3-AB. Relationships among the inhibition by short-chain fatty acids, the activation by p-nitrophenyl acetate, and the influence of bilirubin and L-tryptophan on these effects indicate that the cyanolysis active site and the known primary binding site for indoles are both near, but on opposite sides of, tyrosine-409 of bovine albumin (tyrosine-411 of human albumin).