Creatine kinase isoenzymes in extracts of various human skeletal muscles

We have attempted to "map" creatine kinase (CK; EC 2.7.3.2) anatomically by assaying biopsy specimens of skeletal muscles taken from different locations from 109 surgical patients. Substantial activities of CK-MM were present in every specimen; CK-MB was observed in about 44% of these, at approximately 1 to 6% of the total CK activity.