The further heterogeneity of creatine kinase. Presence of isoenzymes of cathodic mobility in rat tissues.

Supernatant fractions from rat tissue homogenates were examined for creatine kinase (EC 2.7.3.2) isoenzymes by agarose gel electrophoresis at pH 8.6. The distribution of the various isoenzymes, and their relative contributions to the total tissue creatine kinase, is stated. A previously unreported isoenzyme associated with brain and kidney preparations is described. It is a minor contributor to brain creatine-kinase activity but is the major isoenzyme for kidney. The presence of an additional isoenzyme for cardiac tissue was confirmed; this isoenzyme exhibits similar levels of activity to that of the MB isoenzyme.