Nitrogenase change

In general there are few reproducible data on binding of reducible substrates to the isolated MoFe proteins. However, the S = EPR signal from the FeMoco centers of Kpl is pH dependent, the g values changing with a pKa of 8.7 (50). Of course, the proton is a substrate of nitrogenase however, there is no direct evidence for the proton associated with the pKa being bound directly to FeMoco. Nevertheless, this pKa can be perturbed by addition of the analog substrate acety-... 

It is becoming clear that the MgATP hydrolysis is not required to induce protein-protein electron transfer, but its role in nitrogenase function is still undefined. The most likely hypothesis at the moment is that its hydrolysis, on the Fe protein, induces important changes in the MoFe protein, presumably by altering the conformation of the enzyme complex. Nevertheless, the nature of the changes in the MoFe protein remain obscure. 

Fe-protein interacts with MoFe-protein. Correct docking of Fe-protein to MoFe-protein is associated with conformational changes taking place during step 1. Steps 1 and 2 are prerequisites for all following nitrogenase reactions and for substrate reduction. 

In this scheme the electrons are all supplied by the metal, which undergoes a change in oxidation state of six. In nitrogenase, electrons would be supplied from the iron protein and there would be no need for large changes in oxidation state in the molybdenum. 

---