Figure 4.

Top panels: Wireframe mesh representation of the ion charge-density maps calculated around the βLg A dimer in different NaCl concentrations at pH 2.5 (A) and pH 7.5 (B), and represented around a single monomer for clarity. The ion charge density is shown at ion concentrations of 5 mM (red), 10 mM (blue), 15 mM (yellow), and 20 mM (cyan). βLg A is represented in cartoon mode and colored by secondary structure elements (cyan, loops; blue, turns; violet, α-helices; yellow, β-strands). Bottom panels: Ionic atmosphere calculated around a βLg A dimer at pH 2.5 (C) and 7.5 (D) and projected onto a plane parallel to the dimer interface. For clarity, only one monomer of the protein is shown. Positive and negative ion atmospheres are colored in red and blue, respectively, at ±0.1 kT/e- contour levels.