Bioluminescent assay of creatine kinase activity using immobilized firefly extract

A bioluminescent method has been developed for creatine kinase (CK) assay using immobilized firefly extract containing the bioluminescent coimmobilized system: adenylate kinase + luciferase. ADP for the reaction with CK was produced from the initial mixture of AMP and ATP. The ATP formed in the reaction with CK was quantified using firefly luciferase. The lowest detection limit for CK activity was 0.5 +/- 0.2 U/liter in the sample. A linear range of the determined CK activities was 0.5-1000 U/liter. The correlation coefficient between the bioluminescent and spectrophotometric methods was 0.981 (n = 40). The use of immobilized firefly extract for analysis has been shown to be advantageous compared to soluble enzyme.