Structural similarity of chymopapain forms as indicated by circular dichroism

Four chymopapain forms were isolated by high-resolution liquid chromatography on a cation-exchange column. The three major forms possess nearly identical secondary and tertiary structures, as judged from their c.d. spectra; these components showed similar proteolytic activity and Mr values close to that of papain. The fourth isolated component seems to be a mixture of modified proteins.