Nitrogenase molecular weight

The Fe protein of nitrogenase (molecular weight 64,000) has two subunits and a single Fe4S4 unit. Each subunit folds as a single a/p-type domain. It binds with magnesium adenosine triphosphate (MgATP). 

The enzyme, nitrogenase, is composed of two proteins—component I and component II. Component I has a molecular weight of about 220,000 and contains either one or two molybdenum and 24 iron atoms. Compo-... 

An important structural feature, common to both metal-sulfur enzyme centers and (hypothetical) low molecular weight competitive catalysts, certainly is the sulfur coordination of the metals. The type of donor atom represents the most basic structural feature of any metal complex. Functional features indispensable for competitive catalysts are determined by Eq. 44. It expresses the hydrogenase, CO dehydrogenase, and nitrogenase reactions in their most general form. 

Biological N2 fixation is catalyzed by Fe/Mo, Fe/V, or FeFe (the Fe-only) nitrogenases (150, 151). The extremely different reaction conditions of the biological and the Haber-Bosch processes of N2 reduction, that is, standard temperature and pressure and biological redox potentials on the one hand, red-hot temperatures and high pressures on the other hand, make the quest for low molecular weight competitive catalysts particularly challenging. 

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