A structure‐based site‐directed mutagenesis study on the neurolysin (EC 3.4.24.16) and thimet oligopeptidase (EC 3.4.24.15) catalysis

Abstract
Neurolysin (EP24.16) and thimet oligopeptidase (EP24.15) are closely related metalloendopeptidases. Site-directed mutagenesis of Tyr613 (EP24.16) or Tyr612 (EP24.15) to either Phe or Ala promoted a strong reduction of kcat/KM for both enzymes. These data suggest the importance of both hydroxyl group and aromatic ring at this specific position during substrate hydrolysis by these peptidases. Furthermore, the EP24.15 A607G mutant showed a kcat/KM of 2×105 M−1 s−1 for the Abz-GFSIFRQ-EDDnp substrate, similar to that of EP24.16 (kcat/KM=3×105 M−1 s−1) which contains Gly at the corresponding position; the wild type EP24.15 has a kcat/KM of 2.5×104 M−1 s−1 for this substrate