Evaluating apoenzyme–coenzyme–substrate interactions of methane monooxygenase with an engineered active site for electron harvesting: a computational study

low-temperature methane oxidation is one of the greatest challenges in energy research. although methane monooxygenase (mmo) does this catalysis naturally, how to use this biocatalyst in a fuel cell environment where the electrons generated during the oxidation process is harvested and used for energy generation has not yet been investigated. a key requirement to use this enzyme in a fuel cell is wiring of the active site of the enzyme directly to the supporting electrode. in soluble mmo (smmo), two cofactors, i.e., nicotinamide adenine di-nucleotide (nad+) and flavin adenine dinucleotide (fad) provide opportunities for direct attachment of the enzyme system to a supporting electrode. however, once modified to be compatible with a supporting metal electrode via fes functionalization, how the two cofactors respond to complex binding phenomena is not yet understood. using docking and molecular dynamic simulations, modified cofactors interactions with smmo-reductase (smmor) were studied. studies revealed that fad modification with fes did not interfere with binding phenomena. in fact, fes introduction significantly improved the binding affinity of fad and nad+ on smmor. the simulations revealed a clear thermodynamically more favorable electron transport path for the enzyme system. this system can be used as a fuel cell and we can use fes-modified-fad as the anchoring molecule as opposed to using nad+. the overall analysis suggests the strong possibility of building a fuel cell that could catalyze methane oxidation using smmo as the anode biocatalyst.