Cytochrome c oxidase from the liver of bullfrog, Rana catesbeina and change in its turnover rate during metamorphosis

Abstract 1. Cytochrome c oxidase was purified from the liver mitochodria of bullfrog ( Rana catesbeina ). The heme a content of the purified enzyme was 13.5 nmol per mg protein. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed that the enzyme protein was composed of nine polypeptide subunits having molecular weights of 42 000, 27 000, 25 000, 20 000, 15 000, 13 000, 8 600, 5 400 and 3 600. The purified enzyme from the adult frog was immunologically identical with that from the tadpole. 2. The rates of synthesis and degradation of cytochrome c oxidase were 5.2- and 2.0-times higher at metamorphic climax than at premetamorphic stage, respectively. The amount of the enzyme in the liver was highest at metamorphic climax.