Fig. 3. (A) The catalytic cleft of IDO1 is shaped with two pockets: pocket A (yellow surface) is mostly composed of aromatic and hydrophobic residues, while pocket B (magenta surface) is made of one positively charged residue and aromatic residues. (B) Co-crystallized inhibitors (14, 19–21) with shadow colors indicating the part of the chemical structure occupying pocket A (yellow) and/or pocket B (magenta).