Role of amino acid residues in chromogenic substrates cleaved by pancreatic elastase

Abstract

Anionic chromogenic substrates, 3-carboxypropionyl tripeptide p-nitroanilides modified with glycine, β-alanine, alanine, leucine and proline in positions P1, P2, and P3 were synthesized. The substrates were digested with pancreatic elastase and the values of Km, kcat, and kcat/Km were determined. Alanine plays a decisive role in position P1, substrates with glycine or β-alanine in this position are not cleaved. The substitution in P2 is dominant for proline; next follow alanine, leucine, and glycine. The substitution in P3 is the least specific one.