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In vitro synthesis of the iron-molybdenum cofactor of nitrogenase. Purification and characterization of NifB cofactor, the product of NIFB protein.
NifB-co has been purified to homogeneity by a unique one-step method and is stable to repeated freeze-thaw cycles and is also stable in N-methylformamide, the solvent used for the isolation of FeMo-co. Expand
Purification and characterization of the nifN and nifE gene products from Azotobacter vinelandii mutant UW45.
The protein (hereafter referred to as NIFNE) was found to contain equimolar amounts of the nifN and -E gene products and have a native molecular mass of 200 +/- 10 kDa, which indicates an alpha 2 beta 2 structure. Expand
Isolation of an iron-molybdenum cofactor from nitrogenase.
  • V. K. Shah, W. J. Brill
  • Medicine, Chemistry
  • Proceedings of the National Academy of Sciences…
  • 1 August 1977
The FeMoCo might be used as a model for synthesizing catalysts for chemical nitrogen fixation and knowledge of the structure of this cofactor should be useful for understanding the role of molybdenum at the active site of nitrogenase, role of ligands close to moly bdenum in electron and proton transfer, and the catalytic mechanism of nitrogen fixation. Expand
Nitrogenase. IV. Simple method of purification to homogeneity of nitrogenase components from Azotobacter vinelandii.
Extracts of Azotobacter vinelandii have been fractionated by simple techniques to obtain highly purified components of nitrogenase, which form aggregated species upon exposure to air. Expand
In vitro synthesis of the iron-molybdenum cofactor of nitrogenase.
Properties of the partially purified dinitrogenase activated by FeMo-co synthesized in vitro were comparable to those of dinitrogensase from the wild-type organism; e.g., ratios of acetylene- to nitrogen-reduction activities, as well as those ofacetylene reduction activities to EPR spectrum peak height at g = 3.65, were very similar. Expand
Apodinitrogenase: purification, association with a 20-kilodalton protein, and activation by the iron-molybdenum cofactor in the absence of dinitrogenase reductase.
The Azotobacter vinelandii mutant strain UW45 contains a mutation in the nifB gene and produces an inactive dinitrogenase protein that can be activated by the addition of purified iron-molybdenum cofactor (FeMoco), which has now been purified 96-fold to greater than 95% purity and is FeMoco-activatable. Expand
Substrate reduction properties of dinitrogenase activated in vitro are dependent upon the presence of homocitrate or its analogues during iron-molybdenum cofactor synthesis.
The structural features of the homocitrate molecule absolutely required for the synthesis of a catalytically competent iron-molybdenum cofactor were determined to be the hydroxyl group, the 1- and 2-carboxyl groups, and the R configuration of the chiral center. Expand
Citrate substitutes for homocitrate in nitrogenase of a nifV mutant of Klebsiella pneumoniae.
The response of maximum velocities to changes in pH for both the wild-type and the NifV- dinitrogenase was compared and no substantial differences were observed, but there are minor differences. Expand
Molybdenum in nitrogenase.
The biochemical process described by nitrogen fixation is the reduction of N2 to NH3, which can then be used for the synthesis of amino acids, nucleic acids, and other essential nitrogenous compounds, which ranks with photosynthesis as a process of fundamental importance to all life on earth. Expand
The nifY product of Klebsiella pneumoniae is associated with apodinitrogenase and dissociates upon activation with the iron-molybdenum cofactor.
There are aspects of the dissociation and insertion process in K. pneumoniae that are different from that in Azotobacter vinelandii. Expand