An exopeptidase specific for larger hydrophobic amino acids (especially leucine), no cleavage occurs if the next residue is proline (PubMed:8444149). Release of an N-terminal amino acid with a preference for large hydrophobic amino-terminus residues. Binds 1 Ca(2+) per subunit. Binds 2 Zn(2+) ions per subunit. Can be replaced by Mn(2+) or Co(2+) which results in altered specificities (PubMed:8444149). Calcium activates the enzyme, inhibited by 1,10-phenanthroline, EDTA and EGTA (PubMed:2503378). End-product inhibited by L-amino acids (PubMed:15388919). Non-competitively inhibited by NaF and NaH(2)PO(4) (PubMed:17608735). kcat is 390 sec(-1) with Leu-pNA. Stable after heating at 69 degrees Celsius for 5 hours. Monomer. Sold by several companies as an extracellular extract called Pronase. Most experiments use protein purified from a commercial source rather than protein that has been overexpressed. Belongs to the peptidase M28 family. M28A subfamily.