Figure 4.

(A) The ^Dk_cat value at 30 °C is plotted vs the ΔE_a value for WT (black),¹ I553X series (green),⁴³ L546A and L754A (blue),¹⁹ other double-mutant L546A/I553A (orange),⁴⁷ and double-mutant L546A/L754A (red). The vertical dashed line represents the temperature dependence of WT (ΔE_a = 0.9 kcal/mol). (B) Different patterns that connect the changes in R₀ and Ω. A close distance between the H-donor (D) and H-acceptor (A) is expected from the properties of WT SLO. Below and pointing left, the R₀ and Ω change at the same time allowing recovery to WT-like behavior. Below and pointing right, only R₀ gets elongated while the Ω remains the same or even larger as in the case of DM-SLO. The tightness of the spring represents the frequency of DAD sampling, where the increased tightness indicates an increased Ω value, and vice versa.