Enzymatic activity of WT and D67N OaPAC.A, the kinetics of ATP conversion in the dark- and light-adapted state of WT and D67N OaPAC. In the dark, the ATP conversion rate is slightly higher in the D67N mutant (green) than in WT (orange). In the light-adapted state at 0.5 mM ATP the speed of the conversion was higher in the case of the mutant (blue) than in WT (red). B, Michaelis-Menten plot of the enzymatic activity of WT (red) and D67N (blue) under irradiation, vmax is increased in the D67N mutant. OaPAC, photoactivated adenylate cyclase from Oscillatoria acuminata.