1d75: Difference between revisions
New page: left|200px<br /><applet load="1d75" size="450" color="white" frame="true" align="right" spinBox="true" caption="1d75, resolution 2.800Å" /> '''CONFORMATION OF THE... |
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[[Image:1d75.gif|left|200px]]<br /><applet load="1d75" size=" | [[Image:1d75.gif|left|200px]]<br /><applet load="1d75" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="1d75, resolution 2.800Å" /> | caption="1d75, resolution 2.800Å" /> | ||
'''CONFORMATION OF THE GUANINE.8-OXOADENINE BASE PAIRS IN THE CRYSTAL STRUCTURE OF D(CGCGAATT(O8A)GCG)'''<br /> | '''CONFORMATION OF THE GUANINE.8-OXOADENINE BASE PAIRS IN THE CRYSTAL STRUCTURE OF D(CGCGAATT(O8A)GCG)'''<br /> | ||
==Overview== | ==Overview== | ||
The structure of the synthetic deoxydodecamer d(CGCGAATT(O8A)GCG)2 (O8A = | 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 Structure== | ==About this Structure== | ||
1D75 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:// | 1D75 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=1D75 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Brown, T.]] | [[Category: Brown, T.]] | ||
[[Category: Guy, A.]] | [[Category: Guy, A.]] | ||
[[Category: Hunter, W | [[Category: Hunter, W N.]] | ||
[[Category: Leonard, G | [[Category: Leonard, G A.]] | ||
[[Category: Teoule, R.]] | [[Category: Teoule, R.]] | ||
[[Category: b-dna]] | [[Category: b-dna]] | ||
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[[Category: modified]] | [[Category: modified]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 12:13:40 2008'' | ||
Revision as of 13:13, 21 February 2008
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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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