Hydrogenase enzyme shows unique mechanism

Abstract

A team of researchers has marshaled evidence that a recently discovered enzyme works through a mechanism that is startlingly different from other enzymes of its type. The unusual bacterial hydrogenase contains no metal and functions by activating its substrate rather than molecular hydrogen, the investigators conclude. In searching for analogies to shed light on this different mode of reactivity, the researchers compare the catalytic mechanism of the hydrogenase to that of reactions of hydrocarbons in superacid media. Biochemistry professor Rudolf K. Thauer of Max Planck Institute for Terrestrial Microbiology, in Marburg, Germany, isolated hydrogen-forming methylenetetrahydromethanopterin from a primitive bacterium in 1990. As one step on the pathway to producing methane by hydrogenation of carbon dioxide, the enzyme oxidizes its pterin substrate to liberate hydrogen. The dehydrogenase enzyme also catalyzes the reverse reaction, using hydrogen to reduce the pterin, thus making it a hydroge...