FIGURE 2.

Crystal structure of hG9C. a, the overall structure of hG9C is shown with the bound LacNAc (blue), BIPA (yellow), and SiaLac (green). Secondary elements and subsite numbers are also indicated. b, a trimer of hG9C with the three molecules (pink, yellow, and green) in a crystal is shown with a three-fold axis and 6₃ screw axes. Ni²⁺ on the three-fold axis, three coordinated His residues, and the bound LacNAc are also shown. c, area of contact between two molecules (pink and green) with intermolecular hydrogen bonds and metal coordination shown by dotted lines.