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Nucleic Acids Res. 1989 Apr 25;17(8):3229-45.

The propeller DNA conformation of poly(dA).poly(dT).

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  • 1Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.

Abstract

Physical properties of the DNA duplex, poly(dA).poly(dT) differ considerably from the alternating copolymer poly(dAT). A number of molecular models have been used to describe these structures obtained from fiber X-ray diffraction data. The recent solutions of single crystal DNA dodecamer structures with segments of oligo-A.oligo-T have revealed the presence of a high propeller twist in the AT regions which is stabilized by the formation of bifurcated (three-center) hydrogen bonds on the floor of the major groove, involving the N6 amino group of adenine hydrogen bonding to two O4 atoms of adjacent thymine residues on the opposite strand. Here we show that it is possible to incorporate the features of the single crystal analysis, specifically high propeller twist, bifurcated hydrogen bonds, and a narrow minor groove, as well as the close interstrand NMR signal between adenine HC2 and ribose HC1' of the opposite strand, into a model that is fully compatible with the diffraction data obtained from poly(dA).poly(dT).

PMID:
2726457
[PubMed - indexed for MEDLINE]
PMCID:
PMC317725
Free PMC Article
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