9dna
From Proteopedia
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CRYSTAL STRUCTURE ANALYSIS OF AN A-DNA FRAGMENT AT 1.8 ANGSTROMS RESOLUTION. D(GCCCGGGC)
Overview
Single crystals of the self-complementary octadeoxyribonucleotide d(GCCCGGGC) have been analysed by X-ray diffraction methods at a resolution of 1.8 A. The tetragonal unit cell of space group P4(3)2(1)2 has dimensions of a = 43.25 A and c = 24.61 A and contains eight strands of the oligonucleotide. The structure was refined by standard crystallographic techniques to an R factor of 17.1% using 1359 3 sigma structure factor observations. Two strands of the oligonucleotide are related by the crystallographic dyad axis to form a DNA helix in the A conformation. The d(GCCCGGGC) helix is characterized by a wide open major groove, a near perpendicular orientation of base pairs to the helix axis and an unusually small average helix twist angle of 31.3 degrees indicating a slightly underwound helix with 11.5 base pairs per turn. Extensive cross-strand stacking between guanine bases at the central cytosine-guanine step is made possible by a number of local conformational adjustments including a fully extended sugar-phosphate backbone of the central guanosine nucleotide.
About this Structure
9DNA is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Crystal structure analysis of an A-DNA fragment at 1.8 A resolution: d(GCCCGGGC)., Heinemann U, Lauble H, Frank R, Blocker H, Nucleic Acids Res. 1987 Nov 25;15(22):9531-50. PMID:3684603
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