The isolated iron–molybdenum cofactor of nitrogenase catalyses hydrogen evolution at high potential

Abstract

The isolated cofactor of nitrogenase FeMoco catalyses hydrogen evolution at the high potential associated with the FeMoco^ox/semi-red couple (E° = –280 mV vs. NHE , C₆F₅S^– ligated form); analysis of the current–potential dependence of the catalysis suggests a mechanism involving rate-determining loss of H₂ from an FeMoco(H)₂^red intermediate (k = 3 s^–1); the relatively slow kinetics of this step may be related to an obligatory role for hydridic intermediates in substrate reductions by nitrogenase.