7. Proline specific proteases

There are many proline specific peptidases that fall into two classes. Prolidase and aminopeptidase P cleave the N-terminal amino acid from a peptide that is followed by proline at the carbonyl-immino bond. Prolinase and proline imino peptidase cleave proline from the N terminal position of peptides.

Endoproteases that have specificity for proline are HIV-1 protease, prolyl endopeptidase and carboxypeptidase P. HIV-1 protease cleaves at the carbonyl-imino bond. Prolyl endopeptidase and carboxypeptidase P cleave at the carboxyl side of the proline residue.

Many proteases are sensitive to the cis-trans configuration of Xaa-Pro bond including prolyl endopeptidase, prolidase and trypsin when proline is the residue C-terminal to the cleaved di-peptide bond. This isomer specificity has been used to study the kinetics of proline cis-trans isomerization by measuring the rate at which cis-peptides are cleaved by trans specific proteases.