Secondly, to also prevent strong interactions with hydrophobic regions in the system, the C6 dispersion parameter with anything other than water was set to zero, including the other buffers. The latter also avoids clustering of buffers during the simulation. Further details on buffer parameterization are provided in the accompanying paper. Thus, the buffer particles have an σ of 0.25 nm and an of 4 kJmol -1 . In coarse-grained simulations, standard Na + ions were used as buffer particles.