The photoreactive nucleotide 3'-O-(4-benzoyl)benzoyl ADP (BzADP) is not a substrate for photophosphorylation but is a strong competitive inhibitor (K i 2-25μM) with respect to ADP and ATP in photophosphorylation or ATP hydrolysis and Pi-ATP exchange reactions, respectively. The analog binds tightly to the membrane-bound CF1, competes with the right binding of ADP, and prevents the inactivation of the enzyme by tight binding of ADP. Upon irradiation with long wavelength ultraviolet light, the tightly bound BzADP becomes covalently attached to both the α- and β-subunits of the enzyme.
