Abstract
Serum Creatine kinase (CK, EC 2.7.3.2) isoenzyme MM was separated by agarose gel electrophoresis into three sub-bands: CK-MM1, CK-MM2and CK-MM3. In acute myocardial infarction, CK-MM3was markedly elevated at 4-12 hours after onset of symptoms and decreased gradually with time, whereas CK-MM1, which was a major sub-band in healthy individuals, was decreased at early phase of acute myocardial infarction and gradually increased. At 36-48 hours after onset of symptoms, CK-MM sub-band patterns returned to normal (CK-MM1> CK-MM2> CK-MM3) . Since myocardial homogenate had only CK-MM3 sub-band, CK-MM3changed to CK-MM2 and CK-MM1in serum by some converting factor. The physico-chemical properties of the converting factor were examined and the following results were obtained: 1) The converting factor was heat labile and depended on reaction temperature. 2) The activity of the converting factor was activated with metal ion, especially Ca _??_. 3) The activity of the converting factor depended on reaction mixture pH, 7.0-7.5 was optimum. 4) The converting factor, with a molecular weight of 210000 daltons, was dialyzable with concentration by ultrafiltration method. 5) The converting factor was present in protease fraction obtained by CM Affi-Gel Blue chromatography. With these results, we assumed that the converting factor was involved with protease or deaminase.
