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Journal of Nucleic Acids
Volume 2010, Article ID 468017, 6 pages
http://dx.doi.org/10.4061/2010/468017
Research Article

Structure and Stability of a Dimeric G-Quadruplex Formed by Cyclic Oligonucleotides

1Departament de Química Orgànica, Universitat de Barcelona, C/. Martí i Franquès 1, 08028 Barcelona, Spain
2The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
3Instituto de Química Física “Rocasolano”, CSIC, C/. Serrano 119, 28006 Madrid, Spain

Received 15 January 2010; Accepted 12 March 2010

Academic Editor: Daniela Montesarchio

Copyright © 2010 Joan Casals 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

We have studied the structure and stability of the cyclic dodecamer d<pGGGTTAGGGTTA>, containing two copies of the human telomeric repeat. In the presence of sodium, NMR data are consistent with a dimeric structure of the molecule in which two cycles self-associate forming a quadruplex with three guanine tetrads connected by edgewise loops. The two macrocycles are arranged in a parallel way, and the dimeric structure exhibits a high melting temperature. These results indicate that cyclization of the phosphodiester chain does not prevent quadruplex formation, although it affects the global topology of the quadruplex.