2O4F:
reference: Structure of a d(TGGGGT) quadruplex crystallized in the presence of Li+ ions., Creze C, Rinaldi B, Haser R, Bouvet P, Gouet P, Acta Crystallogr D Biol Crystallogr. 2007 Jun;63(Pt 6):682-8. Epub 2007, May 15. PMID: 17505106

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