114d
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INOSINE-ADENINE BASE PAIRS IN A B-DNA DUPLEX
OverviewOverview
The structure of the synthetic deoxydodecamer d(C-G-C-I-A-A-T-T-A-G-C-G), has been determined by single crystal X-ray diffraction techniques at 2.5A, resolution. The refinement converged with a crystallographic residual, R =, 0.19 and the location of 64 solvent molecules. The sequence crystallises, as a B-DNA helix with 10 Watson-Crick base-pairs (4 A.T. and 6 G.C) and 2, inosine.adenine (I.A) pairs. The present work shows that in the, purine.purine base-pairs the adenine adopts syn orientation with respect, to the furanose moiety while the inosine is in the trans (anti), orientation. Two hydrogen bonds link the I.A. base-pair, one between, N-1(I) and N-7(A), the other between O-6(I) and N-6(A). This bulky, purine.purine base-pair is incorporated in the double helix at two, positions with little distortion of either local or global conformation., The pairing observed in this study is presented as a model for I.A, base-pairs in RNA codon-anticodon interactions and may help explain the, thermodynamic stability of inosine containing base-pairs. Conformational, parameters and base stacking interactions are presented and where, appropriate compared with those of the native compound, d(C-G-C-G-A-A-T-T-C-G-C-G) and with other studies of oligonucleotides, containing purine.purine base-pairs.
About this StructureAbout this Structure
114D is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
ReferenceReference
Inosine.adenine base pairs in a B-DNA duplex., Corfield PW, Hunter WN, Brown T, Robinson P, Kennard O, Nucleic Acids Res. 1987 Oct 12;15(19):7935-49. PMID:3671069
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