Figure 8.

Effect of solvent pH on net electrostatic charge of WT and ALS-variant Zn₄-SOD1. A–D). Plot of electrophoretic mobility of rungs of charge ladders of WT and ALS-variant Zn₄-SOD1 (at different pH) against the number of acetylated lysines of each rung; plots are derived from charge ladders shown in Supporting Information Figure S6. (E) The measured and predicted (formal) net charge of WT and ALS-variant Zn₄-SOD1 from pH = 5.5 to 8.0. The formal values of net charge (solid or dashed lines) were calculated as described in Materials and Methods. The measured values of net charge were derived from plots in part A–D. (F) Plot of the “charge gap” (i.e., the difference in net negative charge of variant and WT Zn₄-SOD1) across pH 5.5–8.0.