IMPROVED PURIFICATION OF SLOW MOVING PROTEASE FROM HUMAN GASTRIC MUCOSA AND ITS ACTION ON THE B CHAIN OF OXIDIZED BOVINE INSULIN

Abstract

Slow moving protease (SMP), a non-pepsinogen type acid protease present in human gastric muscosa, was purified to apparent homogeneity by an improved purification procedure including chromatography on DEAE-cellulose, concanavalin A-Sepharose and Sephadex G-150. Upon DEAE-cellulose chromatography, SMP was separated into three fractions, designated SMP-I, SMP-II, and SMP-III. SMP-I was the major component and the other two appeared to be autodigestion products of SMP-I. Investigation on the specificity of action of SMP on the B chain of oxidized insulin revealed that SMP resembles cathepsin E and pepsin A in substrate specificity rather than cathepsin D and pepsin C.