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'Nitrate Reduction' in keywords
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1995 (1)
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1Author    Kassem AlefRequires cookie*
 Title    in Rhodopseudomonas capsulata AD 2  
 Abstract    Nitrate assimilation by Rhodopseudomonas capsulata A D 2 was com pletely inhibited by ammonium only in young well illuminated cultures. At higher densities (A660 about 0.5) the addition o f ammonium had no inhibitory effect, but the nitrate was only reduced to the level o f nitrite, which appeared in the medium. Under both conditions the cellular level o f nitrate reductase activity remained unaffected. In marked contrast to other R. capsulata strains both ammonium sensitive and insensitive cells could reduce nitrate in the light and in the darkness. In the light up to 90% of the reduced nitrate was assim ilated, but in the dark the reduced nitrate was stoichiometrically excreted as nitrite. This behaviour was only shown by R. capsulata A D 2 and BK5, while in other strains the nitrate assim ilation was always com pletely inhibited by ammonium. The role o f photosynthesis and respiration by the regulation o f nitrate reduction is discussed. 
  Reference    Z. Naturforsch. 39c, 85—8 (1984); received Novem ber 10 1983 
  Published    1984 
  Keywords    Nitrate Reduction, Regulation, Rhodopseudomonas capsulata 
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 TEI-XML for    default:Reihe_C/39/ZNC-1984-39c-0085.pdf 
 Identifier    ZNC-1984-39c-0085 
 Volume    39 
2Author    Susanne Bickel-Sandkötter, Martina UferRequires cookie*
 Title    Properties of a Dissimilatory Nitrate Reductase from the Halophilic Archaeon Haloferax volcanii  
 Abstract    Grown under anaerobic conditions in presence of nitrate, Haloferax volcanii shows nitrate reduction and accumulation of nitrite in the culture medium. We found a membrane-asso-ciated nitrate reductase, which could easily be solubilized by gently stirring of isolated mem­ branes. Surprisingly, this nitrate reductase requires no NaCl for its activity. A medium pH of 7.5 and high temperatures up to 80 °C are necessary for optimum activity. Kinetic studies showed that the apparent K M was 0.36 mmol/1 for nitrate and 80 ^mol/1 for dithionite-reduced methyl viologen. The respiratory chain inhibitor cyanide effects nitrate reduction noncompe-titively with respect to nitrate with a K \ of 0.3 mmol/1. Azide was a strong inhibitor: The concentration required for half maximal inhibition was 60 |amol/l, whereas thiocyanate and chlorate were much weaker inhibitors. The isolated enzyme was partially purified by frac­ tionated precipitation using polyethylene glycol. SDS gel electrophoresis resulted in three putative subunits of the nitrate reductase of molecular masses of about 100, 61, and 31 kDa. 
  Reference    Z. Naturforsch. 50c, 365—372 (1995); received February 6/February 27 1995 
  Published    1995 
  Keywords    Archaeon, Haloferax volcanii, Dissimilatory Nitrate Reductase, Nitrate Reduction, Inhibition 
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 TEI-XML for    default:Reihe_C/50/ZNC-1995-50c-0365.pdf 
 Identifier    ZNC-1995-50c-0365 
 Volume    50 
3Author    T. Kentemich, G. Haverkam, H. BotheRequires cookie*
 Title    The Expression of a Third Nitrogenase in the Cyanobacterium Anabaena variabilis  
 Abstract    Physiological experiments indicate that Anabaena variabilis can express either a V-or a Fe-nitrogenase in addition to the conventional, M o-containing enzyme complex. The occur­ rence o f the Fe-nitrogenase in A. variabilis can also be concluded from D N A -D N A hybridiza­ tion experiments using cloned anfW or nifW probes coding for the smaller subunit (= nitroge­ nase reductase) o f the Fe-nitrogenase from Azotobacter vinelandii or for the same subunit o f the M o-nitrogenase from Klebsiella pneumoniae. The cyanobacterium A. variabilis is the first phototroph found to contain all three nitrogenases landii as yet. Vanadium cannot substitute for M o in 
  Reference    Z. Naturforsch. 46c, 217 (1991); received November 2 1990 
  Published    1991 
  Keywords    Alternative N itrogenases, Vanadium-Nitrogenase, Iron-Nitrogenase, Nitrate Reduction, Cyanobacteria, Anabaena variabilis 
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 TEI-XML for    default:Reihe_C/46/ZNC-1991-46c-0217.pdf 
 Identifier    ZNC-1991-46c-0217 
 Volume    46