Fig. 4.
Effect of lipids and cholesterol on EPR spectra of spin-labeled HIV gp41 fusion domain with the MTSL spin label attached at four positions that were mutated to cysteines as indicated. Fusion domains were solubilized in buffer or bound at a peptide:lipid ratio of (at most) 1:900 to 100 mM large unilamellar vesicles composed of POPC:POPG (4:1), POPC:POPG:cholesterol (6:2:2), or POPC:POPG:cholesterol (5:2:3). The gray lines in the spectra taken in the presence of cholesterol are spectra taken in POPC:POPG (4:1) for comparison.