Solvent effects on the conformation of nucleotides. Part 1. The conformation of 5′-adenosine monophosphate in water–dimethyl sulphoxide using nuclear Overhauser effects and lanthanide relaxation probes

Abstract

The conformation of 5′-adenosine monophosphate (AMP) in D₂O and in [²H₆]DMSO was studied using nuclear Overhauser effects together with lanthanide-induced relaxation effects and vicinal coupling constants. The conformation of 5′-AMP through the glycosidic bond was studied in detail using a simple two-state model and continuous distributions derived from potential-energy calculations. Either of the two models clearly indicates a base conformation for 5′-AMP in D₂O within the anti-region and a flexible syn–anti equilibrium in [²H₆]DMSO. These different flexibilities in the two solvents illustrate the importance of solute–solvent interactions in the definition of the conformation of a flexible solute in solution.