10.1021/jm201571p
The study investigated the role of different phosphate groups and adenosine motifs in adenophostin A (AdA), a potent agonist of the D-inositol 1,4,5-triphosphate receptor (IP3R). The researchers synthesized all three possible diphosphate analogs of AdA and glucose 3,4-bisphosphate (7). They found that 2-dephospho-AdA (6), which mimics Ins(4,5)P2, was only 4-fold less potent than IP3, while 7 was 400-fold less potent. Even 3″-dephospho-AdA (5), which lacks one vicinal diphosphate group, has measurable activity. This study concludes that the adenosine motif has a direct role in promoting adenylate cyclase potency that is independent of the 2′-phosphate group and that the vicinal diphosphate motif is not essential for IP3R activity. The results suggest that it may be possible to design potent agonists using only two of the three phosphates, and a model for possible interaction with adenine-R504 supports the activity of 5 and 6.