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| [[Image:1bd1.gif|left|200px]] | | {{Seed}} |
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| {{STRUCTURE_1bd1| PDB=1bd1 | SCENE= }} | | {{STRUCTURE_1bd1| PDB=1bd1 | SCENE= }} |
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| '''CRYSTALLOGRAPHIC STUDY OF ONE TURN OF G/C-RICH B-DNA'''
| | ===CRYSTALLOGRAPHIC STUDY OF ONE TURN OF G/C-RICH B-DNA=== |
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| ==Overview==
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| The DNA decamer d(CCAGGCCTGG) has been studied by X-ray crystallography. At a nominal resolution of 1.6 A, the structure was refined to R = 16.9% using stereochemical restraints. The oligodeoxyribonucleotide forms a straight B-DNA double helix with crystallographic dyad symmetry and ten base-pairs per turn. In the crystal lattice, DNA fragments stack end-to-end along the c-axis to form continuous double helices. The overall helical structure and, notably, the groove dimensions of the decamer are more similar to standard, fiber diffraction-determined B-DNA than A-tract DNA. A unique stacking geometry is observed at the CA/TG base-pair step, where an increased rotation about the helix axis and a sliding motion of the base-pairs along their long axes leads to a superposition of the base rings with neighboring carbonyl and amino functions. Three-center (bifurcated) hydrogen bonds are possible at the CC/GG base-pair steps of the decamer. In their common sequence elements, d(CCAGGCCTGG) and the related G.A mismatch decamer d(CCAAGATTGG) show very similar three-dimensional structures, except that d(CCAGGCCTGG) appears to have a less regularly hydrated minor groove. The paucity of minor groove hydration in the center of the decamer may be a general feature of G/C-rich DNA and explain its relative instability in the B-form of DNA.
| | The line below this paragraph, {{ABSTRACT_PUBMED_2600970}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 2600970 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_2600970}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: B-dna]] | | [[Category: B-dna]] |
| [[Category: Double helix]] | | [[Category: Double helix]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 11:21:25 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 18:51:59 2008'' |
