A Natural Choice for Activating Hydrogen

摘要

Hydrogenases are metalloenzymes that catalyze the activation of molecular hydrogen. Microbes usually use this reaction to produce or oxidize H_2 in energy-related reactions that involve long-range electron transfer. Structures representing the two classes of "classic hydrogenases" have shown that both contain a binuclear metal center. On page 572 of this issue, Shima et al. (1) describe the structure of a third class of hydro-genase, which contains a mononuclear iron center. In this case, activation of an H_2 molecule generates a hydride that is transferred directly to an organic substrate involved in microbial methane production. The structural details revealed by the study are relevant for understanding the H_2-activation stage of the catalytic cycle of classic hydrogenases.