Characterization and Crystal Structure of Prolyl Endopeptidase from Abalone (Haliotis discus hannai)

Abstract Aimed to study the characteristics of prolyl endopeptidase (PEP, EC 3.4.21.26) and its possible role in the degradation of collagen, we cloned the full-length cDNA sequence of PEP from abalone (Haliotis discus hannai) (Hdh-PEP). Recombinant Hdh-PEP (rHdh-PEP) was expressed in vitro, its enzymatic properties were detected, and its secondary structure was analyzed by Circular Dichroism (CD). We for the first time determined the 1.5 A crystal structure of rHdh-PEP. The decomposition effect of rHdh-PEP on collagen peptides was analyzed. Our data revealed that the molecular weight of rHdh-PEP is 85 kDa, consisting of a catalytic domain and a β-propeller domain. The optimal pH and temperature of rHdh-PEP were pH 6.0 and 20 °C, respectively. Using small collagen peptides as substrates, HPLC-ESI-MS analysis confirmed that rHdh-PEP specifically cleaved at the carboxyl side of proline residues, suggesting its role in the degradation of collagen peptides during autolysis.