Figure 4

Detailed structural differences between wild-type mIDH2 and the K256Q mutant. (a,b) A comparison of the electrostatic surfaces of wild-type mIDH2 (a) and the K256Q mutant (b) in the vicinity of the substrate-binding pocket. Isocitrate and Mg²⁺ ions are shown in green. The lysine cluster (Lys127, Lys129, Lys130 and Lys133), Lys256 and Gln256 are indicated by green sticks. (c) The lysine cluster near Lys256 and Gln256. After structural alignment of wild-type mIDH2 (green) and the K256Q mutant (tan), structural differences near the substrate-binding pocket are obvious. Isocitrate and Mg²⁺ ions are colored in magenta. The structures of mIDH2 are superimposed with the crystal structure of human IDH2 (PDB code: 4JAS) and NADP⁺ (from the structure of human IDH2) is shown in orange. Hydrogen bonds are indicated by yellow dashed lines, and bond lengths are shown in black (Å).