Figure 3.

(a) Diffraction pattern taken over a 1° rotation about ϕ with resolution rings marked in Å. A row of three strong Bragg reflections at 3.28–3.31 Å, arising from stacked bases in dsDNA, is highlighted by a green box. These reflections have indices (11 −11 32), (10 −10 33) and (9 −9 34). The row of reflections parallel to c* with Miller indices (0 0 10), (0 0 11), (0 0 12), (0 0 13) and (0 0 14) is marked with a blue box. (b) Self-rotation function at χ = 180°. The a, b and c* axes are marked. Peaks on the b axis indicate the crystallographic twofold screw symmetry, whereas peaks in the ac* plane arise from noncrystallographic twofold symmetry.