“…Despite the mutation, the Fe 3+ is still hexacoordinated, since the free axial coordination position is occupied by a hydroxide anion that protonates with a pK a of 5.6 [ 31 , 32 , 34 , 35 , 40 , 41 , 42 , 43 ]. The latter could easily be replaced by small neutral and anion ligands, such as dioxygen, hydrogen peroxide, and nitrite [ 28 , 29 , 35 , 36 , 37 , 38 , 39 , 44 ]. One of the limitations to the widespread use of enzymes to replace solid-state catalysts is their limited stability in non-aqueous solvents.…”