Abstract
Creatine kinase (CK) was isolated from the mitochondrial fraction obtained from bovine brain by ultracentrifugal separation. Two different sizes of CK-fraction A, low molecular weight, and B, high molecular weight were separated by Sephacryl S-200 column chromatography. Fractions A and B were further separated into fractions A1 and A2, and B1 and B2 by ion exchange column chromatography with DEAE Sephadex CL-6B as a resin. Fractions A1, A2 and B1 migrated to the γ-globulin position, but fraction B2 migrated to the prealbumin position on agarose gel electrophoresis. The former 3 fractions were not inhibited by anti-CK-M antibody. The results indicate that fraction A1, A2 and B1 were mitochondrial CK. Thin-layer gel filtration and Sephacryl S-200 column chromatography revealed that the CK in fraction A1 had a high molecular weight, and the CK in fraction A2 had a low molecular weight, 82, 000 dalton. The Michaelis-Menten constants (Km) of CK in fractions A1 and A2 for creatine phosphate were 0.54-0.87 and 0.47-1.00 mmol/l, respectively. The activation energy of CK in fraction Al was 77.8-99.5 and CK in fraction A2 was 85.7-102.3 kJ/mole. The residual CK activity after heat treatment was 7.4% of CK in fraction A1 and 3.8% of CK in fraction A2. This showed that when purified, mitochondrial CK was more unstable than CK in serum.
