Enkephalin convertase: potent, selective, and irreversible inhibitors

Biproduct analogs of lysine and arginine are potent inhibitors of enkephalin convertase, a carboxypeptidase B-like enzyme which appears to be physiologically associated with enkephalin biosynthesis. The most effective derivatives are guanidinoethylmercaptosuccinic acid and guanidinopropylsuccinic acid with respective Ki's of 8.8 and 7.5 nM. These dicarboxylic acid analogs of arginine are several hundred fold more potent towards enkephalin convertase than towards carboxypeptidase B or N. Kinetic analysis indicates the pure competitive nature of the inhibition. Bromoacetyl-D-arginine, an irreversible inhibitor of carboxypeptidase B and N, is also an efficient irreversible inhibitor of enkephalin convertase.