Human pancreatic enzymes: purification and characterization of a nonelastolytic enzyme, protease E. resembling elastase.

?An enzyme with proteolytic activity has been isolated from activated extracts of human pancreatic tissue. The purification procedure included salt fractionation followed by ion-exchange chromatography on SE-TSephadex C-25 and on DEAE-Sephadex A-50. The homogeneity of this enzyme, designated protease te, was demonstrated by disc electrophoresis and by sedimentation equilibrium centrifugation stidues. The homogeneous enzyme shows the ability to hydrolyze many of the conventional synthetic substrates used for the identification of elastase activity; however, it demonstrates no significant elastolytic activity. A comparison of human protease E with porcine elastase reveals a high degree of similarity between the two proteases with respect to inhibition by active-site directed peptide chloromethyl ketones, stability, decreased susceptibility to naturally occurring proteinase inhibitors, and specificity for synthetic substrates as well as several other physical properties. The major difference between human protease E and porcine elastase, other than the lack of elastolytic activity by human protease E, seems to be in the ionic character and the amino acid composition of these two proteins. Porcine elastase is a cationic enzyme, while human protease E appears to be anionic in nature. These dissimilarities concerning elastolytic activity and ionic character appear to be directly related.