Metalloproteins nitrogenase system

Studies of nitrogenase proteins from the bacteria Azoto-bacter vinelandii and Clostridium pasteurianum have provided structural details of the proteins involved. Two metalloproteins make up the nitrogenase system an Fe... 

Studies of nitrogenase proteins from the bacteria Azoto-bacter vinelandii and Clostridium pasteurianum have provided structural details of the proteins involved. Two metalloproteins make up the nitrogenase system an Fe protein which couples the hydrolysis of ATP to electron transfer, and an FeMo protein which is responsible for binding N2. The dual role of these proteins can be summarized in three steps ... 

The occurrence of Mo in enzymatically active metalloproteins, such as the FeMo-cofactor of the N2-reducing nitrogenase system present in several procaryotes, has... 

Five proteins containing molybdenum are known nitrate reductase, nit-rogenase, xanthine oxidase, aldehyde oxidase and sulphite oxidase. They also contain iron, and the first four are best classified as multi-enzyme systems. Early studies on xanthine oxidase used a number of important ESR techniques, particularly rapid freeze kinetic methods and isotopic substitution in metalloproteins. This work has been reviewed [38, 39], Nitrogenase is the subject of considerable recent interest since it contains detectable iron-sulphur centres but as there is some disagreement at present concerning the interpretations of the results readers are referred to the original literature [40-42]. 

Much of this work has been discussed earlier (Section 2.3.3) in the context of ENDOR spectroscopy of high-spin S > 1/2) systems, as the electronic spin ground state of nitrogenase FeMo-cofactor has S = 3/2. From a historical perspective, this work was one of the earlier applications of ENDOR to metalloprotein systems by the Hoffman laboratory, and owed a great deal of its success to the biochemical expertise of the late William H. Orme-Johnson, one of the pioneers not only of nitrogenase research but of bioinorganic chemistry in general. ... 

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