PURIFICATION AND CHARACTERIZATION OF A NOVEL TYROSYL-AMINOPEPTIDASE FROM HUMAN OSTEOCLASTOMAS

1. An aminopeptidase that preferentially releases tyrosine residues fr om synthetic substrates has been purified from human osteoclastomas. T his enzyme also hydrolyses dipeptides having an N-terminal tyrosine an d a hydrophobic carboxy-terminal amino acid. 2. The tyrosyl-aminopepti dase consists of two identical subunits with M(r)s of about 100,000. 3 . The enzyme is a metallopeptidase and is inhibited by chelating agent s, chloromethylketone analogues of hydrophobic amino acids, and bestat in.