Thierry Le Gall, Saad K. Ibrahim, Carol A. Gormal, Barry E. Smith and Christopher J. Pickett
The isolated cofactor of nitrogenase FeMoco catalyses hydrogen evolution at the high potential associated with the FeMocoox/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)2red 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.