The results discussed in the main text are obtained from Free Energy Perturbation (FEP) simulations -to calculate the hydration free energies of the amino acids -and molecular dynamics (MD) simulations -all other observables, e.g. solvent accessible surface area, dipole moment, numbers of hydrogen bonds -of single copies of the amino acids in water. In addition, FEP simulations of a single CHF 3 in water were used to calculate hydration free energies in the parameterization of fluorocarbon-bound hydrogen (H F ). Also used in the parameterization were simulations of liquid CHF 3 , to calculate its molar volume, and additionally simulations of gas phase CHF 3 , to calculate its vaporization enthalpy.