Pz-peptidase is an endopeptidase that cleaves the synthetic substrate Pt-peptide (4-phenylazobenzyloxycarbonyl-Pro-Leu-Gly-Pro-Arg), which was originally developed for the assay of collagenase. The Pt-peptidase gene of Bacillus licheniformis N22 was cloned and sequenced. The gene consists of 628 amino acids with a motif for zinc-dependent metalloprotease, and shares 42% amino acid identity with the oligoendopeptidase of Lactococcus lactis. This is the first report on the gene structure of a Pz-peptidase.