Conformation, hydrogen bonding and aggregate formation of guanosine 5'-monophosphate and guanosine in dimethylsulfoxide. |
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Authors: | R T West L A Garza nd W R Winchester and J A Walmsley |
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Institution: | R T West, L A Garza, 2nd, W R Winchester, and J A Walmsley |
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Abstract: | 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. |
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