The binding of cobalt(III)-ligated amino acids and peptides to chymotrypsin and trypsin.

The interaction of some metal-ligated amino acids and dipeptides with chymotrypsin and trypsin was examined. Small structural analogues of substrates carrying the positively charged pentamminecobalt(III) group at the carboxyl terminal were synthesized. These compounds do not undergo catalytic conversion but were found to inhibit their target enzyme reversibly. The binding to the active sites was evaluated by kinetic inhibition measurements. The binding affinities of the metal-ligated substrate-analogues were found to be comparable in strength to those of more familiar small specific peptides.