Conformation, hydrogen bonding and aggregate formation of guanosine 5′-monophosphate and guanosine in dimethylsulfoxide

• Published in: Nucleic acids research Vol. 22; no. 23; pp. 5128 - 5134
• Main Authors: West, R. Ted, Garza, Leoncio A., Winchester, William R., Walmsely, Judith A.
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 25.11.1994
• Subjects: Dimethyl Sulfoxide; Guanosine - chemistry; Guanosine Monophosphate - chemistry; Hydrogen Bonding; Inosine Monophosphate - chemistry; Magnetic Resonance Spectroscopy; Nucleic Acid Conformation; Protons; Quaternary Ammonium Compounds - chemistry; Solubility
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/22.23.5128

The tetrabutylammonium salt of guanosine 5′-monophosphate (5′-GMP) dissolves in DMSO-d6 forming aggregated species which exhibit some properties of reverse micelles. 1H NOESY experiments show that the 5′-GMP adopts the syn conformation about the glycosidic bond. Molecular mechanics calculations reveal a stable structure with this conformation in which the phosphate group and the amino group of the base are in close enough proximity to hydrogen bond. In contrast inosine 5′-monophosphate in DMSO-d6, which has no NH2 group for hydrogen bond stabilization of the syn conformation, is shown by NMR to have the anti structure. Guanosine in DMSO-d6 behaves differently from 5′-GMP. Guanosine adopts the anti conformation and forms a symmetric dimer via hydrogen bonding between the N3 and NH2 of the bases.