where E ox and E red are the energies of the oxidized and reduced species, respectively. 4.28 eV is a correction term to bring the potentials on the scale of the standard hydrogen electrode. Note that we decided to use 0.79 eV which is the mean signed error (MSE) obtained from a recent calibration study for Cu enzymes , rather than the MSE originally suggested in ref. 52, since the more recent one is for enzymes resembling LPMOs much more closely.