Analogues of cyclic adenosine 5'-diphosphate ribose and adenophostin A, nucleotides in cellular signal transduction.

Nicotinamide 8-Br-hypoxanthine dinucleotide (8-Br-NHD+) was cyclised at the N-1 position by ADP-ribosyl cyclase from Aplysia californica to give cyclic 8-Br-inosine diphosphoribose, a novel membrane-permeant analogue of cyclic-ADP ribose and agonist in human T cells. Adenine-substituted analogues of adenophostin A with potent Ca2+ releasing activity were synthesized; docking studies using the binding core of the Ins(1,4,5)P3 receptor identified specific residues that could be of importance in determining the hyperagonist nature of adenophostin activity.