FIG. 3.

(a) Approximate block-diagonal form of the dimensionless work-of-charging matrix W for interior dielectric coefficient 3 and Debye length 6.0 Å. The W_ij magnitude categories are as follows: white < 0.05 ≤ dark purple quarter circles < 0.1 ≤ purple half circles < 0.2 ≤ blue 3/4 circles < 0.4 ≤ green triangles < 0.8 ≤ yellow squares < 1.6 ≤ orange pentagons < 3.2 ≤ red circles. The matrix includes all 54 titratable residues used in the present model, which as noted in the text omits the tyrosine residues and four of the cysteine residues; the entire protein contains 174 residues. Designations for the 54 residues considered alternate between left and right (and top and bottom) margins. (b) Cylinders with radii proportional to W_ij mapped onto the PDB 1AMM structure of γ B-crystallin. The W_ij magnitude categories are as follows: 0.4 ≤ green cylinders with three gaps < 0.8 ≤ yellow cylinders with two gaps < 1.6 ≤ orange cylinders with one gap < 3.2 ≤ red cylinders. (c) Lambert projections with potential and charges indicated as in Fig. 1(c). Groups of titratable sites participating in approximate blocks of W are circled in black and numbered in (c) and indicated by black squares in (a). Group numbering corresponds to the order of sites in W in Fig. 3(a), from top to bottom, and group numbers are those to which Figs. 7 and 8 refer. In (b) and (c) the protonation configuration is that modeled to be the most common one at pH 7.1.