Methane has an important role in the global carbon cycle and it has significant economic and environmental consequences. Biological methane is produced solely by an unusual group of archaeal organisms known as methanogens. The metabolic pathway for methane production involves a set of unusual enzymes and cofactors rarely seen outside of methanogenic archaea and anaerobic methane-oxidizing organisms. Among these, one of the most interesting enzymes is methyl-coenzyme M reductase (MCR), which catalyzes the last step in methanogenesis and the first step in anaerobic methane oxidation. MCR contains several unusual modified amino acids, the role of which is mostly unknown. My research project aims to understand why these modifications are found in MCR. The difficult nature of MCR has made it a challenge to elucidate the many mysteries that surround this enzyme. However, using a mix of bioinformatic, genetic and biochemical approaches it is possible to formulate a plan to answer some pertinent questions about this enzyme.