Isolation and characterization of rat pancreatic elastase

Abstract

Proelastase was purified to homogeneity from rat pancreatic tissue by a combination of CM-Sephadex and immobilized protease inhibitor affinity resins. Trypsin activation yields an elastolytic enzyme that possesses a specificity toward small hydrophobic residues in synthetic amide substrates, similar to those of porcine elastase 1 and canine elastase. However, the rat enzyme also rapidly hydrolyzes a substrate containing tyrosine in the P1 position. N-Terminal sequence analysis reveals that rat proelastase has an identical activation peptide with that of porcine proelastase 1 and has 2 conservative amino acid sequence differences from the activation peptide of canine proelastase. The sequence data established that rat proelastase corresponds to the elastase 1 mRNA clone isolated by MacDonald et al. The sequence and substrate data obtained for rat and canine elastases suggest that there is a family of pancreatic elastases with properties similar to those of the classically described porcine elastase 1.