Human brain creatine kinase binding to immobilized cibacron blue F3GA: characterization and use in purification of the enzyme.
Creatine kinase (ATP: creatine N-phosphotransferase, EC 2.7.3.2) from adult human brain grey matter was purified by cibacron blue F3GA-Sepharose affinity chromatography. By gel electrophoresis of the purified enzyme under non-denaturing conditions a single protein band was observed. The dye-bound enzyme was eluted using its substrate, ATP. Reversibility of the binding of purified creatine kinase to blue Sepharose by ATP in a concentration-dependent manner indicated that the cibacron blue molecule which structurally mimics nucleotides occupied the substrate binding site of the enzyme. Also the marked dependence of enzyme binding to blue Sepharose on Mg2+ concentration suggested that Mg2+ ion is capable of combining with the dye moiety to form a site-specific binding complex that is similar to the physiological substrate of creatine kinase, namely Mg(2+)-ATP or Mg(2+)-ADP.