Simple bisubstrate analogs, Ad-E1-Gn, Ad-E2-Gn, and Ad-E3-Gn, are designed to be proto-type adenine-arginine mimetic structures. Both Ad-E1-Gn and Ad-E2-Gn inhibit PKA with IC50 values similar to that of adenosine at 100 p.M ATP and are more potent inhibitors than adenosine at physiologically relevant 2 mM ATP. Ad-E3-Gn is 10-fold less potent than the other two analogs.