Probing the cyclic nucleotide binding sites of cAMP-dependent protein kinases I and II with analogs of adenosine 3',5'-cyclic phosphorothioates.

摘要: A set of cAMP analogs were synthesized that combined exocyclic sulfur substitutions in the equatorial (Rp) or axial (Sp) position cyclophosphate ring with modifications adenine base cAMP. The potency these compounds to inhibit binding [3H]cAMP sites and B from type I (rabbit skeletal muscle) II (bovine myocardium) cAMP-dependent protein kinase was determined quantitatively. On average, Sp isomers had a 5-fold lower affinity for site 30-fold isozyme than their homolog. mean reduction affinities equivalent 20- 4-fold, respectively. Rp showed decrease approximately 400-fold 200-fold B, respectively, I, against 45-fold II. therefore increased relative preference substitution, on other hand, both isozymes. These data show are tolerated differently by two intrachain isozymes They also support hypothesis it is axial, not previously proposed oxygen contributes negative charge ionic interaction an invariant arginine all four sites. In addition, they demonstrate cyclic phosphate can enhance ability discriminate between one as well Since known activation kinases, findings present study have implications synthesis having very high selectivity