Structural Analysis of a Novel Aspartic-Type Endopeptidase from Moringa oleifera Seeds and Its Milk-Clotting Properties.

Abstract

A novel aspartic-type endopeptidase was previously obtained from Moringa oleifera seeds; however, its specific milk-clotting properties have remained unclear. Here, we used various biophysical and molecular simulation approaches for characterizing the structure and function of the aspartic-type endopeptidase. The endopeptidase was preferentially active toward κ-casein (CN) and hydrolyzed it more than calf rennet; however, its ability to hydrolyze α-CN and β-CN was weaker than that of calf rennet. The endopeptidase cleaved κ-CN at Gln135-Asp136 and generated a 15 588.18 Da peptide with 135 amino acids. We further simulated the docking complex of the endopeptidase and κ-CN and found out that they possibly combined with each other via hydrogen bonds. The flocculation reaction between the endopeptidase and κ-CN indicated that milk coagulation occurred within 60 min. Overall, our observations suggest that the aspartic-type endopeptidase can be a potential rennet alternative for cheese making.