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Journal of Nucleic Acids
Volume 2017 (2017), Article ID 6798759, 7 pages
https://doi.org/10.1155/2017/6798759
Research Article

On the Helical Structure of Guanosine 5′-Monophosphate Formed at pH 5: Is It Left- or Right-Handed?

1Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston, ON, Canada K7L 3N6
2Department of Chemistry, Western University, London, ON, Canada N6A 5B7
3Department of Chemistry, University of Ottawa, Ottawa, ON, Canada K1N 6N5

Correspondence should be addressed to Gang Wu; ac.usneeuq@gnaguw

Received 24 July 2017; Accepted 11 October 2017; Published 2 November 2017

Academic Editor: Gary Parkinson

Copyright © 2017 Gang Wu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Early X-ray fiber diffraction studies have established that the spontaneous gel formation of guanosine 5′-monophosphate (5′-GMP) under slightly acidic conditions (e.g., pH 5) results from self-assembly of 5′-GMP into a helical structure in which hydrogen-bonded guanine bases form a continuous helix with 15 nucleotides per 4 turns. For more than five decades, the sense of this helix is believed to be left-handed. Using multinuclear solid-state NMR and IR spectroscopic methods, we have finally determined the long-missing structural details of this helix. First, we found that this 5′-GMP helix is right-handed containing exclusive C3′-endo sugar puckers. Second, we showed that the central channel of this helix is free of Na+ ions, which is in sharp contrast to the helix formed by 5′-GMP at pH 8 where the central channel is filled with Na+ ions.