General Purpose Coarse-Grained Force Field 
Even protons do not escape our coarse-graining strategy! See how Martini protons hop around in a pH dependent way, protonating amino acids, fatty acids, or titratable groups of dendrimers.
F. Grunewald et al., Titratable Martini Model for Constant pH Simulations. J. Chem. Phys, 2020. doi:10.1063/5.