[Irreversible inhibition of adenylate cyclase by oxo-ATP]

Adenylate cyclase from rabbit heart membranes is irreversibly inhibited by 2',3'-dialdehyde of ATP (oxo-ATP). The inhibiting effects is observed during membrane incubation with the inhibitor. Sodium borohydride increase the degree of the enzyme inactivation by oxo-ATP. The substrate protects the enzyme during incubation of the inhibitor with ATP. The data obtained suggest that the effect of oxo-ATP is localized in the enzyme active site and that the inhibitor blocks the amino group of the active site. The values of k2 and Ki for irreversible modification equal to 0.022 min-1 and 5.10(-4) M were determined.