Ligand-based virtual screening (LBVS) and structure-based
virtual
screening (SBVS), and their combinations, are frequently conducted
in modern drug discovery campaigns. As a form of combination, an amalgamation
of methods from ligand- and structure-based information, termed hybrid
VS approaches, has been extensively investigated such as using interaction
fingerprints (IFPs) in combination with machine learning (ML) models.
This approach has the potential to prioritize active compounds in
terms of protein–ligand binding and ligand structural characteristics,
which is assumed to be difficult using either one of the approaches.
Herein, we present an IFP, named the fragmented interaction fingerprint
(FIFI), for hybrid VS approaches. FIFI is constructed from the extended
connectivity fingerprint atom environments of a ligand proximal to
the protein residues in the binding site. Each unique ligand substructure
within each amino acid residue is encoded as a bit in FIFI while retaining
sequence order. From the retrospective evaluation of activity prediction
using a limited number and variety of active compounds for six biological
targets, FIFI consistently showed higher prediction accuracy than
that using previously proposed IFPs. For the same data sets, the screening
performance of LBVS, SBVS sequential VS, parallel VS, and other hybrid
VS approaches was investigated. Compared to these approaches, FIFI
in combination with ML showed overall stable and high prediction accuracy,
except for one target: the kappa opioid receptor, where the extended
connectivity fingerprint combined with ML models showed better performance
than other approaches by wide margins.