Engineering and Directed Evolution of a Ca²⁺ Binding Site A-Deficient AprE Mutant Reveal an Essential Contribution of the Loop Leu₇₅–Leu₈₂ to Enzyme Activity

Figure 2

(a) Emission spectra of wild-type AprE and AprE ΔL₇₅–L₈₂. (Solid squares) wild-type AprE, (Open circles) AprEΔL₇₅–L₈₂. (b) Emission spectra of wild-type AprE and AprE ΔL₇₅–L₈₂ in the presence of 0.5 mM EGTA. (Continuous line) native state; (Dashed line) 0.5 mM EGTA. Assays were performed on 10 mM Pipes, pH 7.5 buffer at room temperature (25°C) using a 1 cm cuvette of 1.5 mL with continuous shaking.

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