Because our approach relies on rigid-body docking, we cannot directly account for the inherent flexibility of the protein targets. However, employing multiple experimentally determined snapshots of the same protein bound to various ligands can partially compensate for this limitation. Such snapshots provide a range of realistic protein conformations, each capable of accommodating different ligands. By considering a collection of these slightly different but physically validated protein conformations, it becomes possible to assess whether a given ligand, in any of its reasonably low-energy quantum-mechanically optimized conformations, can be strongly bound by at least one known protein conformation. For this reason, we have selected 16 high-quality PDB structures of the IDO1 protein: eight containing the heme cofactor and eight without this cofactor. The PDB structures under the code of 2D0T , 5EK2 , 5XE1 , 6E40 , 6E41 , 6E46 , 7E0O , 7E0S have been selected with the heme cofactor and 6AZV , 6E43 , 6V52 , 6WPE , 7RRC , 8ABX , 8FUR , 8I7L without cofactor.