FIGURE 6.

Structures of β-Gal^I51T complexed with galactose or 6S-NBI-DGJ. A, superimposition of the overall structures of the β-Gal^WT-galactose (magenta), β-Gal^WT-6S-NBI-DGJ (green), β-Gal^I51T-galactose (red), and β-Gal^I51T-6S-NBI-DGJ (cyan). Mutated residue I51T is shown in space-filling representation. B, the F_o − F_c electron density map (gray) corresponding to mutated residue Thr-51 of β-Gal^I51T-6S-NBI-DGJ is contoured at 3.0 σ. Shown is the Ile-51 residue of β-Gal^WT-6S-NBI-DGJ (green) and the Thr-51 residue of β-Gal^I51T-6S-NBI-DGJ (cyan).