The Conformation of Pyridine Nucleotides Studied by 31P and 1H Fast Fourier Transform Nuclear Magnetic Resonance Spectroscopy. II. The Backbone Conformation of Dinucleotides

Abstract

Using parameters derived from the component mononucleotides, β-NMN, 5′-AMP, and 5′-ADP, the 31P n.m.r. spectra of oxidized pyridine coenzymes, recorded in the presence of coupling from the ribose protons, are analyzed with the use of extensive computer simulations. It is shown that the spectra are compatible only with gauche–gauche conformation about the C5′—O5′ bonds on both the adenine and nicotinamide ends of oxidized pyridine coenzymes. The 1H and 1H–{31P} Fourier transformed 16K n.m.r. spectra of 5′-AMP and 5′-ADP are reported and their full analysis given, and it is shown that the nucleotides exist predominantly in the gauche–gauche conformation about the C4′—C5′ and C5′—O5′ bonds.