Potentially, this could be related to differences in molecular weight, which is higher for binders than for non-binders (482.9 ± 187.8 vs 341.9 ± 152.8, respectively; p<0.001). However, no evident correlation was found with the binding energy ranking of this set (Fig. ), making it difficult to the determinant factors of the predictive power. These results encouraged us to perform a second and more challenging round of docking simulations, using Validation set 2 to classify ligands as inhibitor binders, substrate binders, or non-binders.