Conformer generation, the assignment of realistic 3D
coordinates
to a small molecule, is fundamental to structure-based drug design.
Conformational ensembles are required for rigid-body matching algorithms,
such as shape-based or pharmacophore approaches, and even methods
that treat the ligand flexibly, such as docking, are dependent on
the quality of the provided conformations due to not sampling all
degrees of freedom (e.g., only sampling torsions). Here, we empirically
elucidate some general principles about the size, diversity, and quality
of the conformational ensembles needed to get the best performance
in common structure-based drug discovery tasks. In many cases, our
findings may parallel “common knowledge” well-known
to practitioners of the field. Nonetheless, we feel that it is valuable
to quantify these conformational effects while reproducing and expanding
upon previous studies. Specifically, we investigate the performance
of a state-of-the-art generative deep learning approach versus a more
classical geometry-based approach, the effect of energy minimization
as a postprocessing step, the effect of ensemble size (maximum number
of conformers), and construction (filtering by root-mean-square deviation
for diversity) and how these choices influence the ability to recapitulate
bioactive conformations and perform pharmacophore screening and molecular
docking.