The histidyl radical (3) has been proposed to be inter-converted to the tyrosyl radical (2), making it part of the protective hole-hopping mechanism. The above comparison between barriers and reaction energies for the formation of 3 and 2, cannot be reconciled with this mechanism. In fact, we find that the formation of a tyrosyl (2) via a histidyl (3) intermediate is generally not feasible with a reaction starting from a Cu(II)-oxyl species (1). However, the LPMOs generally show quite different energetics regarding conversion between 3 and 2: For TaAA9, the conversion (the barrier between 3 and 2) is feasible, and cannot be entirely ruled out, although it is unlikely with the presently employed oxidizing species (1). this conversion for LsAA9 seems not to be possible, regardless of the oxidizing species, since conversion between 3 and 2 has a very high barrier. Another remarkable difference between the LPMOs is that the barrier for formation of the tyrosyl radical (3) is generally larger for LsAA9. A consequence of such differences may be that different LPMOs . For 1 in TaAA9, the triplet is most stable, but the states are (as expected) close in energy with splittings of either 17 and 16 kJ/mol, depending on the functional. This is similar to what most previous studies have found. For LsAA9, the triplet and singlet are essentially degenerate with TPSS (the triplet is less stable, but only by 2 kJ/mol). With B3LYP we obtain a larger splitting of 31 kJ/mol, where the triplet is most stable. Small splittings were also obtained in ref. with a splitting of 12-13 kJ/mol (the triplet being more stable), while ref. obtained the triplet as the ground state but again with small splittings of 5 kJ/mol (TPSS) or 16 kJ/mol (B3LYP). The difference to these previous studies is either that we here use a slightly larger QM region 40 or a different functional in the structure optimization. Notably, we also observe for LsAA9 that TPSS gives an intermediate between the closedshell and open-shell singlet, with a spin distribution similar to that of the B3LYP open-shell singlet but with 2-9 times lower magnitude and high spin contamination. Similar issues with spuriously low spin populations with TPSS were seen in some of our previous calculations, although it was less pronounced in the present calculations for 1 in LsAA9.