FIGURE 2.

α-KG·HC·lysine-binding residues of TtHCS. A, TtHCS·Cu²⁺·α-KG complex; B, TtHCS·Mg²⁺·α-KG complex; C, TtHCS·Cu²⁺·HC complex; D, TtHCS·Co²⁺·Lys complex. Residues interacting with ligands are shown as sticks. Bound Cu²⁺, Mg²⁺, and Co²⁺ ions are shown as orange, purple, and pink spheres, respectively. α-KG, HC, and Lys are shown as yellow, orange, and purple sticks, respectively. Water molecules are shown as red spheres. Hydrogen bonds are shown as dashed lines. F_o − F_c omit electron density maps for α-KG, HC, and Lys are shown as yellow, orange, and purple mesh, respectively, and contoured at 3.0 σ, 3.0 σ, 3.6 σ, and 3.5 σ, for A–D, respectively. Residues from the adjacent subunit are indicated by asterisks.