Enzymatic cyclization of nicotinamide adenine dinucleotide phosphate (NADP)

The ADP-ribosyl cyclase of Aplysia californica catalyzed the conversion of NADP, 3′-NADP and 2′,3′-cyclic NADP into their corresponding cyclic nucleotides (established by NMR, UV, and MS analyses). Cyclic-ADP-ribose-phosphate (cADPRP) was more potent than cADPR in mobilizing calcium in the rat brain microsomal system; the EC50 for cADPRP and cADPR were 9.2 μM and 22 μM respectively.