The Biochemistry of Nitrogen Fixation

Positive DNA hybridization with DNA of some 50 species of N2-fixing bacteria to a probe of the structural genes of Mo nitrogenase indicates that the structure of this nitrogenase has been highly conserved. Consistent with this, the physicochemical properties of purified Mo nitrogenase components have been shown to be very similar they have been extensively reviewed and will only be summarized here (see Refs. 17-20 for primary references). 

The DNA encoding the Fe protein inifH) of some 20 N2-fixing bacteria, ranging from Archaebacteria and Eubacteria to Cyanobacteria, 

As isolated, dithionite-reduced Fe proteins exhibit low-temperature EPR spectra consistent with the presence of mixed interconvertible S = 1/2 and S = 3/2 spin states of the [4Fe-4S] center. The relative intensities of these signals change in the presence of urea or ethane- 

Comparison of the Physicochemical Properties of the Fe Proteins of Different Nitrooenases 

Fe component property Mo nitrogenase V nitrogenase Third nitrogenase 

---