One of the most intriguing features of double-helical DNA is its long-range stiffness and local mobility. The dimensions of the chain observed in hydrodynamic and light-scattering studies are typical of a wormlike system that bends smoothly and gradually into compact macro-molecular forms (Bloomfield et al. 1974). At short chain lengths, there is little deviation from a regular repeating structure, and the chain is best described as a rigid rod. If, on the other hand, the ends of the chain are separated by a sufficient number of intervening residues, the duplex is found to exhibit ideal Gaussian behavior with terminal residues oriented completely at random. The very slow attainment of this limit at chain lengths of 8000 or more nucleotide units, however, is a direct consequence of the restricted bending of the chain backbone (Olson 1979a,b).
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Olson et al. (1983) studied this question.