Conformations of DNA span a wide range, from the usual Watson-Crick B-form helix to the left handed Z-form. Recently it has become clear that there is a broad spectrum of conformations possible. Specifically there are sequence dependent variations in the vicinity of the B-form. It is interesting to consider whether or not these variations are large enough to affect recognition processes. We have investigated solvent effects on the DNA conformations and have found that some specific sequences exhibit smooth bends and some others give sharp bends. Experimentally these bent DNA's exhibit anomolously slow migration in gel electrophoresis and would yield a higher apparent molecular weight. We obtain good fit to a set of experiments on the sequences (VA4T4X)i, (V2A3T3X2)i, (VT4A4X)i, and (VA3T3X)i, where V and X are G or C. The models we have constructed for these sequence yield a broad super-helix of radius 120 A for i = 25, a slightly smaller radius super-helix, a very tightly coiled super-helix, and a nearly straight rod. The moment of inertia about the smallest principal axis of each of these conformations appears to be closely related to the apparent molecular weight.
