Fractionation of C-esterase from the hog's kidney extract

Abstract

C-Esterase was separated from other hydrolytic enzymes in hog''s kidney extract by fractionation on a diethylaminoethylcellulose column. The non-adsorbable protein contained type 1 C-esterase, free of B-esterase and an enzyme (DFPase) hydrolysing diisopropyl phosphorofluoridate. In addition, most of the fractions with DFPase activity contained a second type of C-esterase, predominantly in hidden form, i.e. linked to a native inhibitor. Type II C-esterase is liberated from this inhibitor by treatment with p-chloromercuribenzoate. It differs from type I C-esterase by its sensitivity towards sulphydryl inhibitors and by its stronger adsorbability on diethylaminoethylcellulose. Both C-esterase show an abnormal pH-activity curve towards p-nitrophenyl acetate. With increasing pH the hydrolytic rate rises steadily. This property is also shared by chymotrypsin. The properties of the two types of purified C-esterase can explain most of the observations made on crude enzyme mixtures.