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Interaction of water with oriented DNA in the A- and B-form conformations

1989; Elsevier BV; Volume: 56; Issue: 4 Linguagem: Inglês

10.1016/s0006-3495(89)82715-8

1542-0086

Ralf P. Brandes, A. Rupprecht, David R. Kearns,

Advanced biosensing and bioanalysis techniques

High resolution 2H nuclear magnetic resonance (NMR) was used to investigate the interaction of D20 with solid samples of uniaxially oriented Li-DNA (B-form DNA) and Na-DNA (Aand B-form DNA).At low levels of hydration, 0 -4 D20/nucleotide, the 2H spectra shows a very weak (due to short T2) broad single resonance, sug- gestive of unrestricted rotational diffusion of the water.At -5 or more D20/ nucleotide, the Li-DNA (B-form) spec- tra suddenly exhibit a large doublet splitting, characteristic of partially ordered water.With increasing hydration, the general trend is a decrease of this splitting.From our analysis we show that the DNA water structure reorga- nizes as the DNA is progressively hydrated.The D20 interaction with Na- DNA is rather different than with Li- DNA.Below 10 D20/nucleotide Na-DNA is normally expected to be in the A-form, and a small, or negligible split- ting is observed.In the range 9-19 D20/nucleotide, the splitting increases with increasing hydration.Above -20 D20/nucleotide Na-DNA converts en- tirely to the B-form and the D20 split- tings are then similar to those found in Li-DNA.We show that the complex Na-DNA results obtained in the range 0-20 D20/nucleotide are caused by a mixture of Aand B-DNA in those samples.