This work represents the first comparison of oxidative damage and protective mechanisms in two different LPMOs: we have shown that it is energetically (and kinetically) feasible for TaAA9 and LsAA9 to form both tyrosyl (2) and histidyl (3) radicals. This commensurates with experiments for both TaAA9 and LsAA9, were a number of studies detected 2 for different LPMOs, including TaAA9 36 and LsAA9. The detection of a histidyl radical (3) has only been proposed recently for LsAA9, 41 but our results show that at least the formation of this radical is energetically similar for TaAA9 and LsAA9. In Fig. we compare reactions I-III for both LPMOs using the Cu(II)-oxyl (1) as reference. Note that we have included results involving His78 (LsAA9) and His86 (TaAA9) in the SI (Table and S5) but we will concentrate the discussion on His1 (this does not lead to any change of conclusions).