Daniel Bartfeld

Purification and characterization of a novel tripeptidyl aminopeptidase from Streptomyces lividans 66

An extracellular tripeptidyl aminopeptidase has been purified from Streptomyces lividans 66 cell‐free cultures. The enzyme is a major component of the secreted proteolytic activity. The protease removes only the N‐terminal tripeptide from recombinant human GM‐CSF and IL‐3 but does not cleave recombinant human IL‐6. The enzyme cleaves the synthetic tripeptide substrates APA‐pNA and APM‐pNA but does not cleave substrates with blocked amino terminals. Smaller substrates are not cleaved. The enzyme appears to be a serine protease of 55 kDa molecular weight. The pH optimum is between 7.5 and 8.5 but varies slightly with the substrate. The N‐terminal sequence and amino acid composition have been determined.