Creatine kinase substrate specificity

The reaction stoichiometry is such that for each molecule of ATP reacting, one photon of maxima] intensity at 562 nm is produced. The method, therefore, is the most sensitive method for ATP measurement and much less than one f mol (10 mol) of ATP can be measured. The system becomes absolutely specific for ATP if all the reagents are purified. By linkage to another reaction, this method has been used to assay numerous ATP-speciflc enzymes and their substrates such as creatine kinase, creatine phosphate and triglycerides. 

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