Fig. 3.

M2–cholesterol distance extraction. (A) Carbon–fluorine REDOR dephasing of Cα sites in M2W, M2U, and M2TM peptides. I35, L36, I39, and L40 Cα in M2(22–61) peptides show significant dipolar dephasing by F₇-cholesterol, while V28 and A29 show minimal dephasing. I35 and L36 Cα in M2TM also show negligible dephasing. Best-fit dephasing curves for the proximal (red) and diagonal (green) binding models are both shown. (B) Geometry of a peptide ¹³C spin near two CF₃ groups of cholesterol. Cholesterol can bind in either a proximal mode or a diagonal mode to the tetramer. (C) Top view of the proximal and diagonal binding modes. The CF₃ groups are shown in magenta. (D) Side view of the CF₃ positions in the proximal binding mode, showing the height of the cholesterol tail relative to the TM helices.