Figure 1. Concentration-dependent binding of β₂GPI to PS/PC bilayers containing 20 mol% PS.

The mass, Γ (μg·cm⁻²), of adsorbed protein measured by ellipsometry is plotted as function of time. At t=200 s, β₂GPI (0.5, 1, 2, 3, 4 or 5 nM; top to bottom) was added to the cuvette and the adsorption was monitored by ellipsometry. The inset shows a plot of the initial adsorption rate, as estimated from the best fit of the regression line to the adsorption data measured between 20 and 120 s after addition of β₂GPI to the cuvette. Experiments were performed at ambient temperature (20–22 °C) in Hepes buffer (75 mM NaCl, 10 mM Hepes, pH 7.5) containing 0.5 mg·ml⁻¹ BSA but not containing CaCl₂.