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. 2009 Oct 7;97(7):2089–2097. doi: 10.1016/j.bpj.2009.07.037

Figure 1.

Figure 1

NTII binding to lipid bilayers mimicking the nAChR membrane environment. (A and B) 1H-NMR spectra of 0.3 mM NTII in the presence of DOPC/DOPS/Chol = 3:1:1 (A) and DOPS (B) liposomes, 30 mM KCl, 10 mM NaОАc, pH 5.5, 303 K. The lipid/protein (L/P) molar ratio is indicated on the right of each spectrum. Membrane perturbations upon NTII binding are shown. (C and D) 31P-NMR spectra of a total 26 mM concentration of DOPC/DOPS/Chol = 3:1:1 (C) and 20 mM DOPS (D) multilamellar liposomes, 30 mM KCl, 10 mM NaОАc, pH 5.5, 303 K without and with membrane-bound NTII. Experimental spectra, theoretical approximation, and lineshape decomposition are indicated by gray, black, and dashed lines, respectively. The parameters of 31P-CSA for DOPC and DOPS, liposome deformation (c/a) in the magnetic field, and relative intensities of DOPC and DOPS signals were estimated to be, respectively, (C) without NTII: 39 ± 1 ppm and 51 ± 1 ppm, 1.21 ± 0.05, 75% and 25%; with NTII: 40 ± 1 ppm and 51 ± 1 ppm, 1.15 ± 0.05, 75% and 25%; (D) without NTII: 50 ± 1 ppm, 1.34 ± 0.05, 100%; and with NTII: 50 ± 1 ppm, 31 ± 1 ppm and 0 ppm (isotropic phase), 1.13 ± 0.05, 86%, 13%, and <1%.