9dna

[[Image:9dna.jpg|left|200px]]<br /><applet load="9dna" size="350" color="white" frame="true" align="right" spinBox="true"

caption="9dna, resolution 1.800&Aring;" />

'''CRYSTAL STRUCTURE ANALYSIS OF AN A-DNA FRAGMENT AT 1.8 ANGSTROMS RESOLUTION. D(GCCCGGGC)'''<br />

==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 [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/ ]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9DNA 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:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=3684603 3684603]

[[Category: Protein complex]]

[[Category: Heinemann, U.]]

[[Category: a-dna]]

[[Category: double helix]]

 

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