Fig. 1.

Creatine kinase activity after alkylation by SM. Enzyme activity of rabbit muscle creatine kinase (rmCK) was assayed using a colorimetric assay to monitor ATP conversion as area under the curve (AUC). Normalized activity was calculated from values of the respective AUC of non-treated rmCK control (ctr, activity 1.0). A RmCK was incubated with 4 mM SM for different times before starting the activity measurements. B Activity of rmCK after incubation with different SM concentrations for 15 min, each. AUC normalized to control levels is illustrated. Asterisks indicate significant differences (* < 0.05, ** < 0.01, *** < 0.001, **** < 0.0001) between the control group and time (A) or ctr and SM concentration (B). Data are derived from 3 independent experiments (n = 3)