389d
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| , resolution 1.550Å | |||||||
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| Coordinates: | save as pdb, mmCIF, xml | ||||||
CRYSTAL STRUCTURE OF B-DNA WITH INCORPORATED 2'-DEOXY-2'-FLUORO-ARABINO-FURANOSYL THYMINES: IMPLICATIONS OF CONFORMATIONAL PREORGANIZATION FOR DUPLEX STABILITY
OverviewOverview
The fundamental conformational states of right-handed double helical DNA, the A- and B-forms, are associated with distinct puckers of the sugar moieties. The furanose conformation itself is affected by the steric and electronic nature of the ring substituents. For example, a strongly electronegative substituent at the C2' position, such as in the 2'-deoxy-2'-fluoro ribo furanosyl analogue, will drive the conformational equilibrium towards the C3'- endo type (north). Conversely, the 2'-deoxy-2'-fluoro arabino furanosyl modification with opposite stereochemistry at C2' appears to have a preference for a C2'- endo type pucker (south). Incorporation of 2'-fluoroarabinofuranosyl thymines was previously shown to enhance the thermodynamic stability of B-DNA duplexes. We have determined the crystal structures of the B-DNA dodecamer duplexes [d(CGCGAASSCGCG)]2and [d(CGCGAASTCGCG)]2with incorporated 2'-deoxy-2'-fluoroarabinofuranosyl thymines S (south) at 1.55 A resolution. In the crystal structures, all S residues adopt an O4'- endo conformation (east), well compatible with an overall B-form duplex geometry. In addition to the increased rigidity of S nucleosides, a clathrate-like ordered water structure around the 2'-fluorines may account for the observed larger thermodynamic stability of DNA duplexes containing 2'-deoxy-2'-fluoroarabino thymidines.
About this StructureAbout this Structure
389D is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of B-DNA with incorporated 2'-deoxy-2'-fluoro-arabino-furanosyl thymines: implications of conformational preorganization for duplex stability., Berger I, Tereshko V, Ikeda H, Marquez VE, Egli M, Nucleic Acids Res. 1998 May 15;26(10):2473-80. PMID:9580702
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