A proton relaxation study of the conformations of some purine mononucleotides in aqueous solution

Abstract

A method is described by which conformationally averaged interproton distances in mononucleotides are obtained from measured proton spin-lattice relaxation times and published crystal coordinates of selected mononucleotides. The glycosil conformations of adenosine in D2O and DMSO-d6 and of 5′-AMP, 5′-GMP, 3′-AMP, and 2′-AMP in D2O are examined by quantitative analysis of the conformationally averaged interproton distances in terms of population distributions obtained from potential energy calculations. 5′-AMP strongly prefers a single glycosyl conformation in the anti range. Besides the anti conformation, 5′-GMP has a secondary minimum in the syn region. 3′-AMP, 2′-AMP, and adenosine have more latitude in their glycosyl torsion angle values, with both the syn and anti regions highly populated.