Heterogeneity of mitochondrial creatine kinase

The heterogeneity of cardiac sarcomeric mitochondrial creatine kinase (creatine N-phosphotransferase, EC 2.7.3.2, sMi-CK), namely, brain ubiquitous Mi-CK (uMi-CK) and an atypical Mi-CK detected in the serum of a patient with ovarian cancer, was studied by isoelectric focusing. These Mi-CKs were found to be slightly different from each other with respect to their pIs under the examined conditions. The atypical Mi-CK was found to be an atypically oxidized form of uMi-CK. Results suggest that these heterogeneities of Mi-CK are caused by the genotypes, structures, biological functions and metabolism/dissimilation of Mi-CKs in the mitochondria and intravascular circulation.