Peptidase activity of macromomycin apoprotein.

Macromomycin, an antibiotic and antitumor protein obtained from Streptomyces macromomyceticus, displayed specific aminopeptidase activity. Pure macromomycin degraded the beta-chain of insulin, a few synthetic di- and tripeptides, and a number of proteins of KB cell plasma membrane. The biological activity and the peptidase activity showed similar temperature-dependent patterns suggesting that one protein is responsible for both activities. The apoprotein contained the aminopeptidase activity while the chromophore, which displayed the antibiotic and antitumor activity, did not show any such activity.