Proline Iminopeptidase v Proline Aminopeptidase We're an undergraduate independent research team and we are having trouble purchasing commercial proline iminopeptidase as it is unavailable on Sigma Aldrich and very expensive on other websites. We need to test that this peptidase will cut a series of tripeptides we are synthesizing in e coli. Could we purchase proline **amino** peptidase instead of proline **imino** peptidase; will the peptidase function the same way? This paper says that they are the same, but this paper says that they are different. Does anyone have any experience with this commercial peptidase?

There are two related enzymes that cleave an N-terminal residue. Enzyme 3.4.11.9 cleaves any residue from a peptide when the next residue is proline. Enzyme 3.4.11.5 cleaves an N-terminal proline from a peptide. Unfortunately, it appears that both are sometimes referred to as proline aminopeptidase. However, only 3.4.11.5 is referred to as proline iminopeptidase.

The vendor should certainly specify which enzyme they are offering.