Figure 3
Solubility data in PEG 6000 for selected mutants of RhoGDI (Cooper et al., 2007) plotted on a logarithmic scale following Cohn's equation, logcp = B − Kc, where cp is the protein concentration, c is the precipitant concentration, B is the idealized protein solubility at c = 0 and K is a protein-dependent constant. For all mutants, the solubility in PEG 6000 is systematically lowered and follows the pattern observed by Trevino et al. (2007). Importantly, the K parameter appears unchanged, so that the solubility lines are approximately parallel. The replacement of lysines by alanines causes only a marginal decrease in solubility; the effect is more significant when threonines are introduced and is the largest with tyrosines. Replacing glutamates by alanines causes a significantly larger solubility reduction. Solubility was measured at room temperature at pH 8.0 (buffered) as a function of PEG 6000 concentration. |