1d92
REFINED CRYSTAL STRUCTURE OF AN OCTANUCLEOTIDE DUPLEX WITH G.T MISMATCHED BASE-PAIRS
OverviewOverview
Single crystal X-ray diffraction techniques have been used to determine the structure of the DNA octamer d(G-G-G-G-C-T-C-C) at a resolution of 2.25 A. The asymmetric unit consists of two strands coiled about each other to produce an A-type DNA helix. The double helix contains six G . C Watson-Crick base-pairs and two G . T mismatched base-pairs. The mismatches adopt a "wobble" type structure in which both bases retain their major tautomer forms. The double helix is able to accommodate this G . T pairing with little distortion of the overall helical conformation. Crystals of this octamer melt at a substantially lower temperature than do those of a related octamer also containing two G . T base-pairs. We attribute this destabilization to disruption of the hydration network around the mismatch site combined with changes in intermolecular packing. Full details are given of conformational parameters, base stacking, intermolecular contacts and hydration involving 52 solvent molecules.
About this StructureAbout this Structure
Full crystallographic information is available from OCA.
ReferenceReference
Refined crystal structure of an octanucleotide duplex with G . T mismatched base-pairs., Hunter WN, Kneale G, Brown T, Rabinovich D, Kennard O, J Mol Biol. 1986 Aug 20;190(4):605-18. PMID:3783714 Page seeded by OCA on Fri May 2 13:35:19 2008