Mechanism of Nitrogenase H₂ Formation by Metal-Hydride Protonation Probed by Mediated Electrocatalysis and H/D Isotope Effects.

ABSTRACT: Nitrogenase catalyzes the reduction of dinitrogen (N₂) to two ammonia (NH₃) at its active site FeMo-cofactor through a mechanism involving reductive elimination of two [Fe-H-Fe] bridging hydrides to make H₂. A competing reaction is the protonation of the hydride [Fe-H-Fe] to make H₂. The overall nitrogenase rate-limiting step is associated with ATP-driven electron delivery from Fe protein, precluding isotope effect measurements on substrate reduction steps. Here, we use mediated bioelectrocatalysis to drive electron delivery to the MoFe protein allowing examination of the mechanism of H₂ formation by the metal-hydride protonation reaction. The ratio of catalytic current in mixtures of H₂O and D₂O, the proton inven

SUBMITTER: Khadka N 

PROVIDER: S-EPMC5673097 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature