The initial heavy atom-only models were further refined using the Protein Preparation module in Schrödinger Suite 2019-2 to add hydrogen atoms and optimise the internal hydrogen bonding network. Finally, the models were energy minimised using the OPLS3e force field with charges from the force field and implicit water solvent, and the Polak-Ribier Conjugate Gradient (PRCG) method to gradient <0.05Å. The final minimised models were then analysed using MolProbity and visualised in Pymol v2.1. Molecular dynamics simulations were performed with the Desmond Molecular Dynamics System (D. E. Shaw Research, New York, NY) by using the tools incorporated in the Schrödinger Suite 2019-2. For full details of molecular dynamics simulation conditions see Supporting Information.