The activation phenomena of papain and cathepsin

Abstract

Vit. C -Fe", pyruvic acid -Fe", and succinic acid -Fe" indirectly produced on unpurified papain (but not in purified, inactivated papain) an activation de-pendng on the reduction of fixed S-S proteins to the SH form. When S-S proteins were added to it, the above-named complexes activated purified papain. Similar results were obtained with cathepsin. Papain and cathepsin in the active state were probably SH proteins; in the reversibly inactivated forms, they appeared to be S-S proteins. The real activators were sulfhydryl compounds.