Figure 10.

Activation of ProT^QQQ by SC(1–246) WT or double mutants. ProT^QQQ (1, 10, or 20 nm) and SC(1–246) WT (black circles) and a representative selection of mutants (navy blue, I1A2; red, L1T2; dark green, L1Q2; brown, V1V2; purple, A1K2; green, A1W2; cyan, K1A2; yellow, Q1K2; eggplant, E1S2) were incubated for 10 min at 25 °C, and the reaction was initiated by adding S-2238. Activation of ProT^QQQ was measured by the relative rates of increase in absorbance at 405 nm, and weak-binding mutants with low activation potency were titrated up to 1300 nm. The data were analyzed as described under “Experimental Procedures.”