Implementation of the QUBE Force Field for High-Throughput Alchemical Free Energy Calculations

The quantum mechanical bespoke (QUBE) force field approach has been developed to facilitate the automated derivation of potential energy function parameters for modelling protein-ligand binding. To date the approach has been validated in the context of Monte Carlo simulations of protein-ligand complexes. We describe here the implementation of the QUBE force field in the alchemical free energy calculation molecular dynamics simulation package SOMD. The implementation is validated by computing relative binding free energies for two congeneric series of non-nucleoside inhibitors of HIV-1 reverse transcriptase using QUBE and AMBER/GAFF force fields. The availability of QUBE in a modern simulation package that makes efficient use of GPU acceleration will greatly facilitate future high-throughput alchemical free energy calculation studies.