1d75
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CONFORMATION OF THE GUANINE.8-OXOADENINE BASE PAIRS IN THE CRYSTAL STRUCTURE OF D(CGCGAATT(O8A)GCG)
OverviewOverview
The structure of the synthetic deoxydodecamer d(CGCGAATT(O8A)GCG)2 (O8A =, 8-oxoadenine) has been determined by single-crystal X-ray diffraction, techniques. The oligonucleotide crystallizes in the orthorhombic space, group P2(1)2(1)2(1) with cell dimensions of a = 25.48 A, b = 41.84 A, and, c = 64.91 A. The refinement has converged with an R-factor of 0.151 for, 1119 reflections in the resolution range 8.0-2.25 A. Sixty-seven solvent, molecules were located during the course of the refinement. The B-DNA, helix consists of ten Watson-Crick base pairs and two guanine-8-oxoadenine, (G.O8A) base pairs. In order to achieve hydrogen-bonding complementarity, between the two bases, an unusual G(anti).O8A-(syn) wobble conformation is, adopted. It is proposed that the G.O8A mispairs are held together by a, network of four interbase hydrogen bonds which are the result of the, formation of two reverse three-center hydrogen-bonding systems. These, involve one carbonyl oxygen lone pair interacting with two hydrogen atoms., In a departure from previous observations of the characteristics of, purine-purine anti-syn base pairs, lambda 1 and lambda 2, the angles, between the glycosidic bonds and the C1'-C1' vector, are symmetric. A, reassessment of the other purine-purine mispairs suggests that similar, three-center hydrogen bonds may occur and make a contribution to, stabilizing other base pairings.
About this StructureAbout this Structure
1D75 is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
ReferenceReference
Conformation of guanine-8-oxoadenine base pairs in the crystal structure of d(CGCGAATT(O8A)GCG)., Leonard GA, Guy A, Brown T, Teoule R, Hunter WN, Biochemistry. 1992 Sep 15;31(36):8415-20. PMID:1390625
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