Using Short Molecular Dynamics Simulations to Determine the Important
Features of Interactions in Antibody--Protein Complexes
Abstract
The last few years have seen the rapid proliferation of machine
learning- (ML) based binding protein design methods. Although these
methods have shown large increases in experimental success rates
compared to prior approaches, the majority of their predictions fail
when experimentally tested. It is evident that computational methods
still struggle to distinguish the features of real protein binding
interfaces from false predictions. To identify features of interactions
that should occur in protein binding interfaces, short molecular
dynamics simulations of 20 antibody-protein complexes were conducted.
Intermolecular salt bridges, hydrogen bonds, and hydrophobic
interactions were evaluated for their persistences, energies, and
stabilities during the simulations. It was determined that only hydrogen
bonds where both residues are stabilized in the bound complex are
expected to persist and contribute meaningfully to the binding between
proteins. In contrast, stabilization was not a requirement for salt
bridges and hydrophobic interactions to persist but interactions where
both residues are stabilized in the bound complex persist significantly
longer and have significantly stronger energies. Using a dataset of 220
real antibody- protein complexes and 8194 false complexes from docking,
a random forest classifier was trained and tested using features of the
expected persistent interactions and compared to one only using the
complex-level features of interaction energy (IE), buried surface area
(BSA), IE/BSA, and shape complementarity. Inclusion of the features of
the expected persistent interactions reduced the false positive rate of
the classifier by two to five fold across a range of true positive
classification rates.