Tilt, nucleic acid conformation

From the measured CD of films of nucleic acids under conditions where X-ray diffraction measurements have been done [17], the general correlations shown in Figure 6 were obtained. The A, B and C-forms of DNA differ slightly in the number of base pairs per turn (11 for A-form, 10 for B-form and 9.33 for C-form), in the tilt of the bases and in the radius of the helix. Moore and Wagner [18] have used a random sequence of bases in the different geometries to calculate CD curves in fair agreement with experiment. It should be possible to deduce conformations different from A, B or C-form by a careful comparison between measured and calculated CD. 

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