title: Peroxidase-coupled method for kinetic colorimetry of total creatine kinase activity in serum.
abstract: We describe a peroxidase-coupled method involving a colorimetric indicator reaction for determining the total activity of creatine kinase (EC 2.7.3.2) in serum. The kinetically favorable reverse reaction is exploited to generate adenosine 5'-triphosphate, which is used in the glycerol kinase-catalyzed phosphorylation of glycerol. The glycerol 3-phosphate so generated is oxidized in the presence of alpha-glycerophosphate oxidase to produce hydrogen peroxide, which is reduced in the presence of peroxidase with the simultaneous oxidation and coupling of 4-aminoantipyrene and 2-hydroxy-3,5-dichlorobenzenesulfonate to produce an intensely colored red chromogen. Results of the proposed method (y) correlate well with those of the Boehringer-Mannheim "CK-NAC UV" method as applied to the Hitachi 705 chemistry analyzer (y = 1.025 chi - 18.1, r = 0.9985, n = 100, range = 19-4531 U/L). The sensitivity of the method, based on molar absorptivities, is nearly fourfold that of procedures involving the reduction of NADP+.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D001663:Bilirubin; D004796:Clinical Enzyme Tests / Q000379:methods*; D003124:Colorimetry / Q000379:methods; D003402:Creatine Kinase / Q000097:blood*; D005978:Glutathione / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D005991:Glycerol Kinase / Q000032:analysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes; D007700:Kinetics; D008274:Magnesium / Q000032:analysis; D015636:Magnesium Chloride; D009203:Myocardial Infarction / Q000175:diagnosis; D010544:Peroxidases / Q000378:metabolism; D011933:Reagent Kits, Diagnostic
chemical_list: D007527:Isoenzymes; D011933:Reagent Kits, Diagnostic; D015636:Magnesium Chloride; D000255:Adenosine Triphosphate; D010544:Peroxidases; D005991:Glycerol Kinase; D003402:Creatine Kinase; D005978:Glutathione; D008274:Magnesium; D005990:Glycerol; D001663:Bilirubin