E is the interaction energy (kcal/mol), between the LEF (in V/Å) of the protein environment and the dipole moment μ (in Debye) of the heme species, while θ is the angle between the dipole moment and LEF vectors. These calculations were done for the RC,TS (Cpd I/substrate) and the Cpd II/substrate-radical species for each reaction. The GAUSSIAN convention was used for the positive directions of the two dipoles. 41