Enzymic, electrophoretic and immunoreactive properties of labeled MM and BB isoenzymes of human creatine kinase.

Purified MM and BB isoenzymes of human creatine kinase (CK) were labeled with Bolton-Hunter reagent. Labeling process did not affect their enzymic activity, although the labeled enzymes lost enzymic activity in storage. The labeled BB isoenzyme progressively changed its electrophoretic mobility, while labeled MM isoenzyme did not. Both labeled isoenzymes, however, maintained their immunoreactivity with their respective antisera. These results suggest that the enzymic and the immunoreactive sites of each CK isoenzyme are different and that BB isoenzyme, not MM isoenzyme, is electrophoretically unstable.