Elsevier, Bioorganic and Medicinal Chemistry, 4(13), p. 1037-1044
DOI: 10.1016/j.bmc.2004.11.037
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In this paper we report the synthesis and the structural characterization of two modified oligodeoxyribonucleotides (ODNs), namely d(A8MeGGGT) and d(TA8MeGGGT), where A8Me represents a 8-methyl-2'-deoxyadenosine. Both ODNs have been studied by 1H NMR, CD spectroscopy and molecular modelling and shown to form fourfolds symmetric G-quadruplex structures, with all strands parallel and equivalent to each other. The complexes are characterized by thermal stabilities comparable to that of their natural counterparts. NOE patterns involving 8-methyl group in A8Me residues allowed us to define the main structural features at the 5'-end of the complexes. Particularly, inter- and intrastrand NOEs show a syn-orientation and a symmetrical arrangement of A8Me bases stacking on the adjacent G-tetrad.