Figure 3.

The R7 and R8 structures, showing surface cysteine residues. (A) Stereo image of the “active site” of R7. The disulfide and basic substitutions are shown in ball-and-stick format. The ordered C-terminal segment is shown in cyan, and C-terminal residues that are near the disulfide are shown in ball-and-stick format. (B) F_o − F_c omit map of the R7 disulfide, contoured at 3σ. (C) The “active site” of R8, with cysteines and substitutions shown in ball-and-stick format. 2F_o − F_c map, contoured at 1σ, is also shown for these residues. Figure produced with PyMOL version 0.98 (DeLano Scientific).