Mitochondrial creatine kinase from human heart muscle: purification and characterization of the crystallized isoenzyme.
An isoenzyme of creatine kinase [ATP: creatine N-phosphotransferase, EC 2.7.3.2] was isolated in pure, crystalline form from mitochondria of human heart muscle. The enzyme has a molecular weight of 84,000 and consists of two subunits with identical molecular weight, each containing two reactive sulfhydryl groups. The enzyme has a specific activity of 15 +/- 2 U/mg in the direction of creatine phosphate synthesis at optimum pH of 8.7 and of 45 +/- 5 U/mg in the direction of ATP synthesis at optimum pH of 6.7. Mitochondrial creatine kinase has Michaelis constants of 1.70 mM for MgATP2-, 8.00 mM for creatine, 0.15 mM for MgADP-, and 3.00 mM for creatine phosphate. The mitochondrial enzyme differs from the other creatine kinase isoenzymes, i.e. from muscle (CK-MM), brain (CK-BB), and their hybrid form (CK-MB) in (I) its amino acid composition and its amino terminal amino acid sequence, (II) its electrophoretic mobility, and (III) its immunological properties. It thus constitutes a fourth isoenzyme of creatine kinase. By analogy to CK-MM, CK-BB, and CK-MB, the mitochondrial isoenzyme was designated as CK-MiMi.
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D003402:Creatine Kinase / Q000302:isolation & purification* / Q000378:metabolism; D003460:Crystallization; D004285:Dogs; D006801:Humans; D007106:Immune Sera; D005779:Immunodiffusion; D007527:Isoenzymes; D007700:Kinetics; D008929:Mitochondria, Heart / Q000201:enzymology*; D008970:Molecular Weight; D055503:Protein Multimerization; D011863:Radioimmunoassay; D013045:Species Specificity
D007106:Immune Sera; D007527:Isoenzymes; D003402:Creatine Kinase