Evaluating Apoenzyme-Coenzyme-Substrate Interactions of Methane Monooxygenase with an Engineered Active Site for Electron-Harvesting: A Computational Study

Abstract

Energy generation via natural gas is viewed as one of the most promising environmentally friendly solutions for ever-increasing energy demand. Of the several alternatives available, natural gas-powered fuel cells are considered to be one of the most efficient for producing energy.

Biocatalysts, present in methanotrophs, known as methane monooxygenases (MMOs) are well known for their ability to quite effectively activate and oxidize methane at low temperature. To utilize MMOs effectively in a fuel cell, the enzymes should be directly attached onto the anode. However, there is a knowledge gap on how to attach MMOs to an electrode and once attached the impact of active site modification on enzyme functionality.

The overall goal of this work was to computationally evaluate the feasibility of attaching MMOs to a metal electrode and evaluate its functionality using docking and molecular dynamic (MD) simulations. It is surmised that MMOs could be attached to a metal electrode by engineering the active site, i.e., Flavin Adenine Dinucleotide (FAD) coenzyme to attract metal clusters (surfaces) via Fe-S functionalization and such modification will keep the active site functionality unfettered. This work was geared toward performing a structural analysis to identify the spatial distribution of FAD binding site(s) in correlation to Nicotinamide Adenine Dinucleotide (NAD) and subsequently to evaluate the feasibility of utilizing FeS-functionalized FAD for anchoring the enzyme system to a metal electrode.

This work is intended to provide valuable mechanistic insights on critical chemical reactions that occur within the apoenzyme/coenzyme system and electron transport pathways so that future researchers could utilize the knowledge when fabricating MMO-based electrodes to be used in fuel cells.