FURTHER HETEROGENEITY DEMONSTRATED FOR SERUM CREATINE-KINASE ISOENZYME MM

Abstract

Serum creatine kinase (EC 2.1.3.2) isoenzyme MM was resolved by isoelectric focusing into a 5-band pattern which gradually changed after the onset of myocardial infarction. Similar changes were demonstrated in patients undergoing coronary-bypass surgery. The evolution of 2 CK-MB sub-bands was studied in both cases. Three electrophoretic bands (CK-MM, pl [isolectric point] 7.10; MM1, pl 6.88; MB1, pl 5.61) were predominant in patterns for sera collected during the early phase of myocardial infarction, but rapidly disappeared during the following hours; bands of increased electrophoretic mobility (MM2, pl 6.70; MM3, pl 6.45; MM4, pl 6.25; MB2, pl 5.34) gradually increased. MM3 was always the major band at the end of the observation period in acute myocardial infarction (mean, 61.4% of total creatine kinase activity 36 h after the peak value for total creatine kinase in serum). The CK-MM bands were present in the serum of patients without heart disease. Changes in the electrophoretic pattern were induced by a thermolabile factor in normal human serum, which transformed the muscular or myocardial MM and MM1 bands after their release into the blood stream.