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 4

Ribbon diagram of the crystal structure of native subtilisin BPN (from coordinates obtained from [21]), drawn using the program Discovery Studio (http://www.accelerys.com/). Relative locations of the catalytic residues and mutations are indicated.