The dye-oxidized or dithionite-reduced forms of the MoFe protein of molybdenum nitrogenase of Azotobacter chroococcum were shown to bind 2 mol of MgADP/mol of protein, as determined by column equilibrium techniques. The gel-filtration elution profile of unbound Mg[14C]ADP was not symmetrical, consistent with a low rate of dissociation from the protein. Symmetrical elution profiles were observed for the oxidized Fe protein of nitrogenase, which bound 2 mol of MgADP/mol of protein. The low rate of dissociation of MgADP from MoFe protein was shown by non-equilibrium column techniques, where 1 mol of MgADP/mol of MoFe protein remained tightly bound during chromatography. Very weak binding of MgATP (less than 0.01 mol of MgATP/mol of MoFe protein) to dye-oxidized but not to dithionite-reduced MoFe protein was observed. These results are discussed in terms of their relevance to the catalytic cycle of nitrogenase catalysis.
Research Article| November 01 1989
Molybdenum nitrogenase of Azotobacter chroococcum. Tight binding of MgADP to the MoFe protein
R W Miller;
Biochem J (1989) 263 (3): 725–729.
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R W Miller, R R Eady; Molybdenum nitrogenase of Azotobacter chroococcum. Tight binding of MgADP to the MoFe protein. Biochem J 1 November 1989; 263 (3): 725–729. doi: https://doi.org/10.1042/bj2630725
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