Analytical ultracentrifugation of the nitrogenase of Azotobacter vinelandii under anaerobic conditions

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Item Type:	Article
Title:	Analytical ultracentrifugation of the nitrogenase of Azotobacter vinelandii under anaerobic conditions
Creators Name:	Behlke, J. and Ristau, O.
Abstract:	Nitrogenase (Azotobacter vinelandii) is a high-molecular-mass enzyme complex responsible for the fixation and metabolization of nitrogen. The complex consists of two different moieties, a larger MoFe protein (240 kDa) and a smaller Fe protein (60 kDa). The stoichiometry and affinity of both components were studied in solution by sedimentation equilibrium in an XL-A analytical ultracentrifuge. Because both components are highly sensitive to oxygen, the experiments were carried out in an argon atmosphere. Data analysis performed using the program Polymole yielded a 2:1 stoichiometry of Fe protein to MoFe protein. Assuming two independent binding sites on the MoFe protein, the association constant for the first Fe protein bound was (1.99 +/- 0.48) x 107 M-1.
Keywords:	Nitrogenase, Sedimentation Equilibrium, Complex Formation, Association Constants, Argon
Source:	Progress Colloid Polymers Science
ISSN:	0340-255x
Volume:	113
Page Range:	182-184
Date:	1999
Official Publication:	https://doi.org/10.1007/3-540-48703-4_26

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