FIG 2.

Comparison of –myrMA and +myrMA binding to stBLMs that contain DOPC and DOPS. The buffer consisted of 10 mM Na₂PO₄ and 50 mM NaCl (pH 7.4). (A) Representative SPR curves of –myr MA binding, analyzed with the Langmuir model (equation 1). (B) Representative SPR curves for +myrMA. Binding to 100% DOPS stBLMs showed significant deviations from a Langmuir isotherm and was analyzed with the Hill model (equation 2), yielding a Hill coefficient of n ≈ 2. (C) Free binding energies, ΔG (equation 3), derived from the data shown in panels A and B. (D) Saturation protein surface densities, R_∞. Lines are guides to the eye, indicating saturation of the equilibrium protein load for stBLMs containing more than ∼40 mol% DOPS. The R_∞ value for +myrMA binding to a 100% DOPS stBLM is excluded from the plot, since it was determined using a different binding model. Measurements were performed at least in triplicate; error bars in panels C and D indicate standard mean deviations from the average. For low-affinity isotherms, it was not possible to measure full binding curves due to limitations in available amounts of protein.