Mechanistic insights into nitrogen fixation by nitrogenase enzymes

Abstract

Biological nitrogen fixation by nitrogenase enzymes is a process that activates dinitrogen (N₂) one of the most inert molecules in nature, within the confines of a living organism and at ambient conditions. Despite decades of study, there are still no complete explanations as to how this is possible. Here we describe a model of N₂ reduction using the Mo-containing nitrogenase (FeMoco) that can explain the reactivity of the active site via a series of electrochemical steps that reversibly unseal a highly reactive Fe edge site. Our model can explain the 8 proton–electron transfers involved in biological ammonia synthesis within the kinetic scheme of Lowe and Thorneley, the obligatory formation of one H₂ per N₂ reduced, and the behavior of known inhibitors.