While there are some differences between the two employed functionals, both agree that the activation energies are consistently lower for TaAA9: we obtain a barrier of 44 kJ/mol (28 kJ/mol with TPSS), compared to a reaction barrier of 77 kJ/mol for LsAA9 (38 kJ/mol with TPSS). Both functionals also agree that the reaction is exothermic. In fact, the final reaction energies are quite similar between the two proteins, where we obtain an energy of -35 kJ/mol for TaAA9 (-76 kJ/mol with TPSS) and -44 kJ/mol for LsAA9 (-75 kJ/mol with TPSS). The result is qualitatively similar to previous calculations for LsAA9 where a smaller QM region was employed; 40 here the reaction barrier for reaction I was predicted to be 64 kJ/mol (53 kJ/mol with TPSS). We can thus conclude that LsAA9 and TaAA9 are likely to form the same tyrosyl intermediate, albeit with different kinetics. .