FIGURE 1.

Scattering intensity profiles are shown for different SpdCl₃ concentrations. The area under the scattering curve for each concentration is normalized to 1. In terms of the Bragg spacing between helices, D_Br, the scattering parameter q = 2π/D_Br. There is virtually no difference in scattering profiles for 0.5, 2, 10, and 20 mM SpdCl3 (solid lines). At 40, 60, and 70 mM SpdCl₃ (dashed lines), a scattering shoulder at lower q-values is increasingly apparent. At 80 and 100 mM SpdCl₃ (dotted lines), the scattering profile is again symmetric, but with a much broader width and larger spacing than at lower SpdCl₃ concentrations. All samples also contained 10 mM TrisCl (pH 7.5) and were equilibrated at 20°C.