Purification and characterization of two human pancreatic elastases

Abstract

Two proteases with elastolytic activity (elastases 1 and 2) have been isolated from activated extracts of human pancreatic tissue. The purification procedure for both elastases included ammonium sulfate fractionation followed by ion-exchange chromatography on CM-Sephadex C-50. Elastase 1 was further purified by chromatography on DEAE-Sephadex A-50. The homogeneity of both enzymes was demonstrated by Sephadex G-75 gel filtration, analytical polyacrylamide disc gel electrophoresis at pH 2.3, 4.5, and 8.3, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis at pH 8.3. Both enzymes hydrolyzed undyed elastin as well as Remazol brilliant blue elastin and Congo red elastin. Activities and kinetic parameters using several synthetic substrates are also reported. The enzymes were further characterized in terms of molecular weight, amino acid composition, and N-terminal and penultimate amino acid residues. Their inhibition by the human serum protease inhibitors alpha2-macroglobulin and alpha1-antitrypsin was also studied. Elastase 1 appears to be very similar to human protease E (Mallory, P. A., and Travis, J. (1975), Biochemistry 14, 722). Elastase 2 is distinct from all human pancreatic proteases which have been characterized to date.