A new photoaffinity analog of cGMP : potent inhibitor of cyclic nucleotide phosphodiesterase

A purine nucleotide analog, 2'-O-(4-benzoylbenzoyl)guanosine cyclic 3',5'-monophosphate (BBcGMP), was synthesized from 4-benzoylbenzoic acid and cGMP. BBcGMP was found to inhibit several types of cyclic nucleotide phosphodiesterases (PDEs) at low concentrations. Besides its activity as a PDE inhibitor, the benzophenone moiety of BBcGMP provides it with UV light-induced photoreactivity toward organic compounds. This photoreactivity of BBcGMP was exploited to radiolabel specifically the light-stimulated cGMP PDE of the rod outer segment with [α- 32 P]BBcGMP. These results suggest that benzoylbenzoic derivatives of cyclic nucleotides can be of general use in the inhibition of cyclic nucleotide PDEs. The results further suggest that radiolabeled cyclic nucleotide derivatives may be useful in the identification and active site determination of cyclic nucleotide-binding proteins and enzymes