Leffler plots for single, double, and triple mutations in helix 1 of barnase plus Ala → Gly scanning at position 12 in the mutant Tyr-17 → Gly. The mutants are as follows: Asp-8 → Ala, Asp-12 → Gly, Asp-12 → Ala, Tyr-13 → Ala, Tyr-13 → Ala/Thr-16 → Ser, Tyr-13 → Ala/Tyr-17 → Ala, Tyr-13 → Ala/Thr-16 → Ser/Tyr-17 → Ala, Gln-15 → Ile, Thr-16 → Ala, Thr-16 → Gly, Thr-16 → Ser, Thr-16 → Ser/Tyr-17 → Ala, Thr-16 → Arg, Tyr-17 → Ala, His-18 → Lys, His-18 → Gln, Tyr-17 → Ala, Tyr-17 → Gly, His-18 → Ala, His-18 → Gly, Asp-12 → Ala/Tyr-17 → Gly, and Asp-12 → Gly/Tyr-17 → Gly.