Can a guinea pig liver enzyme be converted into the serum type?

Details

Researchers purified guinea pig serum L-asparaginase approximately 3,000-fold using sodium sulfate fractionation, methanol precipitation, DEAE-cellulose column chromatography, continuous free-flow electrophoresis, and polyacrylamide gel electrophoresis. The overall yield of purified enzyme was 7%. The enzyme protein appeared as a single pure component in polyacrylamide gel electrophoresis, immunoelectrophoresis, and immunodiffusion.

Digestion with papain converted guinea pig liver L-asparaginase into the guinea pig serum type. After purification by DEAE-cellulose column chromatography and polyacrylamide gel electrophoresis, the papain-digested liver enzyme had essentially the same specific activity as the 3,000-fold purified serum enzyme. There was no quantitative difference in tumor-inhibitory action between the papain-digested asparaginase and the guinea pig serum enzyme.

The two enzymes had identical elution patterns on DEAE-cellulose columns and identical mobilities in polyacrylamide gel electrophoresis, and immunodiffusion showed a reaction of identity. Both enzymes showed a positive glycoprotein stain reaction after polyacrylamide gel electrophoresis. Despite these similarities, the papain-digested liver enzyme and the serum enzyme were not completely identical. Slight differences in amino acid composition and different electrophoretic mobilities in agar gel indicated that they were not equivalent.