Isolation and Characterization of Human Skeletal Muscle Creatine Kinase

Human skeletal muscle creatine kinase was purified by isoelectric focusing with a yield of greater than 60%. Two enzymic proteins, differing in specific activity, were obtained, and each final product produced only a single protein band when examined by electrophoretic methods. The proteins were composed of two subunits of about 41, 000 daltons each, and the amino acid compositions were similar.