Arylamidase activity of neutral proteinase from Saccharomonospora canescens. Comparison with other Zn-proteinases that exhibit the same activity

Abstract

The arylamidase activity of Zn-proteinase from Saccharomonospora canescens (NPS) was studied with series of peptide nitroanilides of varying amino acid sequence and N-acyl blocking groups. The partial mapping of the enzyme S₁, S₂, S₃, S₄ subsites shows that variations in all positions P₁ to P₄ in the substrate structure affect the catalytic efficiency. The importance of P₄–S₄ and P₁–S₁ interactions, which is a characteristic feature of the serine proteinases, is evidenced for the studied Zn-proteinases NPS and serralysin too. The presence of arylamidase activity in the case of Zn-proteinases—astacin EC 3.4.24.21 and serralysin EC 3.4.24.40 is correlated with some specific characteristics of their active site structure: penta-coordinated Zn²⁺ and a tyrosyl residue as a fifth ligand to the Zn²⁺. It is assumed that this tyrosyl residue plays a role in the productive binding and stabilization of the tetrahedral adduct formed during the reaction of enzyme-catalysed hydrolysis of peptide arylamides of corresponding length and sequence.