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Title: The Bi-Loop, a new general four-stranded DNA motif
Author: Salisbury, S. A.
Wilson, S. E.
Powell, H. R.
Kennard, O.
Lubini, P.
Sheldrick, G. M.
Escaja Sánchez, Nuria
Alazzouzi, E.
Grandas Sagarra, Anna
Pedroso Muller, Enrique
Keywords: ADN
Models moleculars
Molecular models
Issue Date: 27-May-1997
Publisher: National Academy of Sciences
Abstract: The crystal structure of the cyclic octanucleotide d<pATTCATTC> contains two independent molecules that form a novel quadruplex by means of intermolecular Watson-Crick A.T pairs and base stacking. A virtually identical quadruplex composed of G.C pairs was found by earlier x-ray analysis of the linear heptamer d(GCATGCT), when the DNA was looped in the crystal. The close correspondence between these two structures of markedly dissimilar oligonucleotides suggests that they are both examples of a previously unrecognized motif. Their nucleotide sequences have little in common except for two separated 5'-purine-pyrimidine dinucleotides forming the quadruplex, and by implication these so-called 'bi-loops' could occur widely in natural DNA. Such structures provide a mechanism for noncovalent linking of polynucleotides in vivo. Their capacity to associate by base stacking, demonstrated in the crystal structure of d(GCATGCT), creates a compact molecular framework made up of four DNA chains within which strand exchange could take place.
Note: Reproducció del document publicat a:
It is part of: Proceedings of the National Academy of Sciences of the United States of America - PNAS, 1997, vol. 94, num. 11, p. 5515-5518
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ISSN: 0027-8424
Appears in Collections:Articles publicats en revistes (Química Inorgànica i Orgànica)

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