Copper coordination in formylglycine generating enzymes

Formylglycine generating enzyme is a copper and oxygen-dependent protein, which catalyzes C–H activation, namely the transformation of peptidyl cysteine to formylglycine. No crystal structures of the enzyme containing copper were published so far. Here, we show by combinations of density functional theory with force fields in the QM/MM approach how copper can be incorporated in the enzyme based on two crystal structures containing Ag(I) and Cd(II) in place of Cu(I) and Cu(II). While we find a linear coordination for Cu(I) and a distorted octahedral environment for Cu(II) we also find the possibility of tetrahedral coordinations in both cases. This structural flexibility may allow the enzyme to catalyze the redox process and accommodate copper in both oxidation states