Fig. 14. Binding mode of imidazothiazole derivative 21 (shown in green carbon atom sticks) to IDO1 resulting from crystallographic studies (pdb code: ; 4PK6). Phe226 and Arg231 are labeled and shown in sticks. Ligand-induced conformational changes are highlighted with dashed arrows from positions observed in the Amg-1 (20) bound crystal structure of IDO1 (Phe226 and Arg231 shown in yellow atom sticks, pdb code: ; 4PK6) to actual positions in the ligand 21 bound complex (Phe226 and Arg231 shown in green atom sticks, pdb code: ; 4PK5).