Decoding the Nitrogenase Mechanism: The Homologue Approach

摘要

Tnhe (Mo)-nitrogenase is a complex metalloenzymenthat catalyzes the key step in the global nitrogenncycle, the reduction of atmospheric dinitrogen (N2)tonbioavailable ammonia (NH3), at the iron moly-nbdenum cofactor (FeMoco) site of its molybdenumniron (MoFe) protein component. Despite the funda-nmental significance of biological nitrogen fixation andnextensive studies over the past decades, the catalyticnmechanism of nitrogenase has not been deciphered.nOne major challenge for the mechanistic study ofnnitrogenase is the redox versatility of its FeMoco cen-nter. The ability of FeMoco to shuttle between oxidationnstates in a rapid and unsynchronized manner results inna mixed oxidation state of the cofactor population dur-ning turnover. The substrate and the various intermediates can only interact with the FeMoco site in a transient manner, sonit is extremely difficult to capture any substrate- or intermediate-bound form of nitrogenase for the direct examination ofnsubstrate enzyme interactions during catalysis.