Cytochrome c modified by digestion with proteolytic enzymes: 1. Digestion

Abstract

Digestion of cytochrome c by pepsin produced an autoxidizable pigment. During the digestion the total amt. of cytochrome present, autoxidizable and non-autoxidizable, showed a rapid initial drop and a slow subsequent rise. Digestion with papain in absence of an activator raised the Fe content of cytochrome c from 0.34 to 0.43% without affecting its catalytic activity. In presence of an activator papain produced an autoxidizable pigment. Digestion with trypsin produced an autoxidizable pigment while chymotrypsin produced a mixture of autoxidizable and non-autoxidizable pigments. The non-autoxidizable part of this mixture, when isolated, contained 0.34% Fe. None of the autoxidizable pigments was active in the succinic oxidase system or in the cytochrome oxidase system with p-phenylenediamine as substrate.