Internal motions in DNA.

Abstract
The 31P and 1H NMR parameters of fractionated double-stranded DNA fragments 600, 300 and 150 base pairs long were measured. Inside an intact double helix, both the deoxyribose and the sugar-phosphate backbone of the helix fluctuate substantially from their equilibrium geometry. The time constant for those coupled motions is of the order of 1 ns.