The Comparative Enzymology of Creatine Kinases

Abstract The two chicken creatine kinases from brain and from muscle have been purified as well as the chicken hybrid enzyme. The brain and muscle enzymes from the rabbit have also been purified and compared to the chicken enzymes. There are significant differences in amino acid composition between the brain and muscle types; the hybrid enzyme has an intermediate composition. Peptide maps of the muscle and brain types further indicate that the sequences of the two types are considerably different. Antibodies prepared against the chicken muscle type enzyme do not cross-react, as measured by complement fixation methods or by Ouchterlony tests, with the chicken brain type enzymes; antibodies against the purified brain type enzyme do not react with the muscle type enzyme. However, the hybrid enzyme reacts with both antibodies, although quantitatively less than with the pure enzymes. The two brain type enzymes from the chicken and rabbit, or the two muscle enzymes, are more similar in their properties than are the brain and muscle forms of one species.