Structural biology - The enzyme at the end of the food chain

Whenever biomass is degraded, and oxygen runs out, the methanogenic bacteria appear and make profuse amounts of methane. The structure of the enzyme that produces it, methyl-coenzyme M reductase, has now been worked out. The structure of the nickel centre and its interaction with substrates reveal the mechanism of one of the few organometallic reactions in biochemistry. Because the methanogens belong to the Archaea, one of the ancient divisions of organisms, the new work also gives a glimpse into what may have been one of the earliest forms of metabolism.