Determination of the solution conformation of adenosein 2':3'-monophosphate by nuclear magnetic resonance with lanthanide probes.

The aqueous solution conformation of adenosine 2':3'-monophosphate at pH 2.5 has been determined by a nuclear magnetic resonance method utilizing lanthanide ions as shift and relaxation probes. The ribose conformation is best described as a rapid equilibrium of 2'-endo(3'-exo) and 3'-endo(2'-exo) conformations in a ratio of approximately 2 to 1. The orientation of the base relative to ribose is restricted to a narrow range about chiCN=-70 degrees.