Figure 5.

Ribbon representation of the E. coli β-galactosidase subunit structure (14). The CNO atoms of the six amino acid mutations that conferred the fucosidase activity are shown with stick representation. Two mutations in the active site (Asp604 and Gln572) are shown in red. Two mutations in close proximity of the active site (Pro511 and Asp908) are shown in magenta. Two mutations far away from the active site and on the protein surface (Val9 and Gln135) are shown in green. The rest of the substrate binding and active site residues are shown in yellow.