FIGURE 3.

OCD of alamethicin in aligned multiple bilayers of di18:0(9.10Br)PC, measured at normal incidence. The I state was measured at full hydration at P/L = 1:20, representing the OCD of alamethicin orienting perpendicular to the bilayer. The S state was measured at full hydration at P/L = 1:100, representing the OCD of alamethicin orienting parallel to the bilayer (33,37). The sample P/L = 1:20 measured at 42% RH has the spectrum shown by a solid line, which is fit by a linear combination of S and I (dash line), indicating that 30% of the alamethicin helices were oriented perpendicular to the substrate (see Ding et al. (37) for details).