Chromogenic substrate for the assay of collagenase and thimet oligopeptidase (Pz-peptidase, metalloendopeptidase 24.15, collagenase-like peptidase). Enzymatic cleavage yields Pz-Pro-Leu-OH, abs45127365/66 (or Pz-Pro-OH, abs45124942/23). The cleavage can be monitored by analytical HPLC, detection at 320 nm.