A, crystal structure of LinB WT (Protein Data Bank code 1MJ5) (gray schematic) with CAVER-calculated tunnels shown in sphere representation as follows: p1a tunnel (cyan), p1b tunnel (magenta), and p2 tunnel (orange). B, model structure of LinB L177W with tunnels, same color-coding as for LinB WT. C, LinB WT in surface representation, clipped through the active site and p1b tunnel. The catalytic residues and halide-stabilizing residues are shown in stick representation (Leu-177, light red), together with the 2-bromoethanol product docked in the active site with AutoDock 4.0 and the bromide ion. The position of the modeled Trp-177 (dark red) is shown for reference.