Unfortunately, in the case of E channel, there are only two ligands with experimentally measured K d , so that the linear calibration clearly leads to an overestimated dissociation constants (e.g. for Vina score -10 it produces K d in a picomolar range, which is too good to be true). On contrary, the equation above produces more realistic K d , in the range of 1-10 nM for the top performing ligands.