Dinitrogenase reductase

As indicated, a number of laboratories got into the process of purifying the components of nitrogenase, so it is difficult to credit any particular laboratory with first success in the endeavor In 1972,Tsoetol. [22] reported purification of dinitrogenase and dinitrogenase reductase to the highest specific activities reported up to that time. Preparations from different organisms require modification of the techniques. Winter and Burris [23] reported a table of activities of components prepared up to 1976. 

Dinitrogenase has been crystallized and its tertiary structure determined by Kim and Rees. [44, 45,46] As indicated, an Fe-Mo unit serves at the active site. Electrons are furnished to this active unit by the Fe enzyme dinitrogenase reductase. The two units together constitute nitrogenase. 

Ludden, P.W. and R.H. Burris. Removal of an adenine-like molecule during activation of dinitrogenase reductase from RhodospirUlum rubrum. Proc. Nad. Acad. Sci. USA 76,6201-6205 (1979). 

PDB ID 1 N2C) (a) In this ribbon diagram, the dinitrogenase subunits are shown in gray and pink, the dinitrogenase reductase subunits in blue and green. The bound ADP is red. Note the 4Fe-4S complex (Fe atoms orange, S atoms yellow) and the iron-molybdenum cofactor (Mo... 

Dumer, J., Bohm, L, Knorzer, O. C., and Boger, P. (1996). Proteolytic degradation of dinitrogenase reductase from Anabaena variabilis (ATCC 29413) as a consequence of ATP depletion and impact of oxygen. /. Bacterial. 178, 606—610. 

All species that can fix nitrogen possess the nitrogenase complex. Its structure, similar in all species so far investigated, consists of two proteins called dinitro-genase and dinitrogenase reductase. Dinitrogenase (240 kD), also referred to as Fe-Mo protein, is an a -heterotetramer that contains two molybdenum (Mo) atoms, and 30 iron atoms. It catalyzes the reaction N2 + 8 H+ + 8 —> 2... 

NH3 + H2. Dinitrogenase reductase (60 kD) (also referred to as Fe protein) is a dimer containing identical subunits. 

The action of the Mo-nitrogenase enzyme involves the functioning of two separately isolatable component proteins, as sketched in Figure 1.21k. The larger of the two proteins, sometimes incorrectlydesignateddinitrogenase has, in the past, been called molybdoferredoxin, azofermo, or component I. More often this protein is called the MoFe or FeMo protein ([MoFe] or [FeMo]). The smaller protein, formerly called azoferredoxin or component II, is sometimes incorrectly referred to " as dinitrogenase reductase. This protein is properly... 

Biological nitrogen fixation is carried out by a highly conserved complex of proteins called the nitrogenase complex (Fig. 22-2), the crucial components of which are dinitrogenase reductase and dinitrogenase... 

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