Comparison of enzymatic characteristics of creatine kinase BB from human healthy and tumor stomach tissues.

Creatine kinase (ATP: creatine N-phosphotransferase, EC 2.7.3.2, CK) BB isoenzyme from stomach tumor tissue was partially purified and its characteristics were compared with those from healthy tissue. Molecular mass of tumor CK-BB was estimated to be 82 000 by polyacrylamide gel electrophoresis. Tumor CK-BB was separated into 2 main subbands around pH 4.5 and 11, minor subbands around pH 5-7.5 by agarose isoelectric focusing. The isoenzyme reacted with anti-human brain CK-BB antibodies and formed a hybrid, CK-MB, with CK-MM prepared from healthy human skeletal muscle. The above physicochemical and immunological characteristics of tumor CK-BB were the same as those of normal CK-BB from normal stomach tissue. Optimum pH of tumor CK-BB was more acidic than that of normal CK-BB. Affinity for creatine phosphate and heat sensitivity of tumor CK-BB were slightly lower than those of normal CK-BB. Tumor CK-BB was more stable after iodoacetamide and urea treatments.