Molybdenum and vanadium nitrogenases of Azotobacter chroococcum. Low temperature favours N2 reduction by vanadium nitrogenase
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چکیده
منابع مشابه
The molybdenum and vanadium nitrogenases of Azotobacter chroococcum: effect of elevated temperature on N2 reduction.
During the reduction of N2 by V-nitrogenase at 30 degrees C, some hydrazine (N2H4) is formed as a product in addition to NH3 [Dilworth and Eady (1991) Biochem. J. 277, 465-468]. We show here the following. (1) That over the temperature range 30-45 degrees C the apparent Km for the reduction of N2 to yield these products is the same, but increases from 30 to 58 kPa of N2. On increasing the tempe...
متن کاملThe vanadium nitrogenase of Azotobacter chroococcum
1. Nitrogenase activity of a strain of Azotobacter chroococcum lacking the structural genes of Monitrogenase (nifHDK) was associated with a V+Fe-containing protein and an Fe-containing protein [Robson, Eady, Richardson, Miller, Hawkins & Postgate (1986) Nature (London) 322, 388-390; Eady, Robson, Richardson, Miller & Hawkins (1987) Biochem. J. 244, 197-207]. 2. The Fe protein was purifed to hom...
متن کاملHydrazine is a product of dinitrogen reduction by the vanadium-nitrogenase from Azotobacter chroococcum.
During the enzymic reduction of N2 to NH3 by Mo-nitrogenase, free hydrazine (N2H4) is not detectable, but an enzyme-bound intermediate can be made to yield N2H4 by quenching the enzyme during turnover [Thorneley, Eady & Lowe (1978) Nature (London) 272, 557-558]. In contrast, we show here that the V-nitrogenase of Azotobacter chroococcum produces a small but significant amount of free N2H4 (up t...
متن کاملThe vanadium nitrogenase of Azotobacter chroococcum. Purification and properties of the VFe protein.
1. Nitrogenase activity of a strain of Azotobacter chroococcum lacking the structural genes for conventional nitrogenase (nifHDK) was separated into two components: an Fe-containing protein and a vanadoprotein. 2. The larger protein was purified to homogeneity by the criterion of electrophoresis of 10% (w/v) acrylamide gels in the presence of SDS. Two types of subunit, of Mr 50,000 and 55,000, ...
متن کاملTemperature-Dependent Regulation by Molybdenum and Vanadium of Expression of the Structural Genes Encoding Three Nitrogenases in Azotobacter vinelandii.
Temperature affects the expression of the three different nitrogenases in Azotobacter vinelandii. Molybdenum repressed the vnfH and anfH operons relatively more at 30 degrees C than at 20 degrees C; at 14 degrees C molybdenum did not repress these genes at all. Similarly, V repressed the anf operon at 30 degrees C but not at 20 or 14 degrees C. Mo was poorly transported into cells grown at the ...
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ژورنال
عنوان ژورنال: Biochemical Journal
سال: 1988
ISSN: 0264-6021,1470-8728
DOI: 10.1042/bj2560429