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00925njm 22002777a 4500 dc Viladoms Claverol, Júlia author Escaja Sánchez, Nuria author Frieden, Mirian author Gómez-Pinto, Irene author Pedroso Muller, Enrique author González, Carlos author 2020-03-30T07:58:27Z 2020-03-30T07:58:27Z 2009-03-24 2020-03-30T07:58:27Z In addition to the better known guanine-quadruplex, four-stranded nucleic acid structures can be formed by tetrads resulting from the association of Watson-Crick base pairs. When such association occurs through the minor groove side of the base pairs, the resulting structure presents distinctive features, clearly different from quadruplex structures containing planar G-tetrads. Although we have found this unusual DNA motif in a number of cyclic oligonucleotides, this is the first time that this DNA motif is found in linear oligonucleotides in solution, demonstrating that cyclization is not required to stabilize minor groove tetrads in solution. In this article, we have determined the solution structure of two linear octamers of sequence d(TGCTTCGT) and d(TCGTTGCT), and their cyclic analogue d<pCGCTCCGT>, utilizing 2D NMR spectroscopy and restrained molecular dynamics. These three molecules self-associate forming symmetric dimers stabilized by a novel kind of minor groove C:G:G:C tetrad, in which the pattern of hydrogen bonds differs from previously reported ones. We hypothesize that these quadruplex structures can be formed by many different DNA sequences, but its observation in linear oligonucleotides is usually hampered by competing Watson-Crick duplexes. Síntesi de l'ADN Oligonucleòtids Síntesi orgànica DNA synthesis Oligonucleotides Organic synthesis Self-association of short DNA loops through minor groove C:G:G:C tetrads