Direct electron transfer of lytic polysaccharide monooxygenases (LPMOs) and determination of their formal potentials by large amplitude Fourier transform alternating current cyclic voltammetry

MtLPMO9 and FoLPMO9 are two lytic polysaccharide monooxygenases (LPMOs), from the filamentous fungi Thermothelomyces thermophila and Fusarium oxysporum, respectively. In the present study an attempt has been made to achieve direct electron transfer between these enzymes and a glassy carbon electrode by immobilization in Nafion polyelectrolyte. The method used to ascertain the feasibility of direct electron transfer was large amplitude Fourier transform alternating current voltammetry (FTacV) and the formal potentials of these enzymes were determined at different temperatures. The findings of this paper indicate that LPMOs can be studied by direct electron transfer, which could be exploited in the near future for their biochemical characterization.