Mechanisms of peptide hydrolysis by aspartyl and metalloproteases

Peptide hydrolysis has been involved in a wide range of biological, biotechnological, and industrial applications. In this perspective, the mechanisms of three distinct peptide bond cleaving enzymes, beta secretase (BACE1), insulin degrading enzyme (IDE), and bovine lens leucine aminopeptidase (BILAP), have been discussed. BACE1 is a catalytic Asp dyad [Asp, Asp^-] containing aspartyl protease, while IDE and BILAP are mononuclear [Zn(His, His, Glu)] and binuclear [Zn1(Asp, Glu, Asp)-Zn2(Lys, Glu, Asp, Asp)] core possessing metallopeptidases, respectively. Specifically, enzyme-substrate interactions and the roles of metal ion(s), the ligand environment, second coordination shell residues, and the protein environment in the functioning of these enzymes have been elucidated. This information will be useful to design small inhibitors, activators, and synthetic analogues of these enzymes for biomedical, biotechnological, and industrial applications.