Isolation of highly active papaya peptidases A and B from commercial chymopapain.

Four enzyme fractions were isolated from commercial chymopapain (EC 3.4.22.6) by chromatography on carboxymethyl cellulose CM-32 and were further purified on an agarose-mercurial column. Two fractions proved to be different forms of chymopapain B, the other two were papaya peptidase A and papaya peptidase B. The two latter enzymes were examined in detail. In contrast to previous findings, papaya peptidases exhibited high specific activity, similar to that of papain, (EC 3.4.22.2) and contained about 1 mol-SH group per mol enzyme. These results are not consistent with the idea that the essential -SH group of papaya peptidase A is 'masked' in the native state, but rather suggest that previous preparations contained a substantial amount of inactive enzyme.