Figure 9
Calculation of the dependence of M1 charge on pH. (a) Dependence of the surface coverage of mica with M1 protein on pH of the working buffer solution. Protein concentration was 2 × 10−3 mg/ml. All data points are averaged from five independent AFM images. (b) Dependence of the surface coverage of mica with M1 protein on electrolyte concentration. Protein concentration was 2 × 10−3 mg/ml, pH of working buffer solution was equal to 7.1. All data points are averaged from five independent AFM images. Solid line is the fit of the experimental data with the Eq. (11) with the parameters r 0 = 1.9 nm, ε = 10, E h = 5.2 ± 0.7 k B T, q = 1.3 ± 0.2 elementary charges. (c) Calculated from the Eq. 11 dependence of the surface coverage of mica with M1 protein on protein charge. (d) Dependence of the protein charge on the pH of the working buffer solution. circles – values of the protein charge obtained by combination of plots (a) and (c); triangles – the data obtained from electrophoresis experiments in 5 mM NaCl, 2.5 mM MES buffer with M1 concentration of 0.05 mg/ml by Eq. 12 for r 0 = 2.9 nm, ε = 80.
