Fig. 4.
(A) O2 activation reaction coordinate of the ternary complex with pterin carbonyl bound to FeII (green) and without the pterin carbonyl bound to FeII (red). (B) The geometries for the ternary, superoxo, and peroxo complexes in the reaction coordinate with the pterin carbonyl bound. The red dashed ovals demonstrate the proton transfer from the pterin cofactor to a nearby carboxylate residue. (C and D) Qualitative electronic structures and electron transfer pathways for the superoxo and TS structures for (C) the reaction coordinate with the pterin carbonyl bound and (D) the reaction coordinate without the pterin carbonyl bound to FeII.