Nitrate Reduction by a Dicarboxylate Shuttle in a Reconstituted System from Spinach Leaves

1980 ◽  
Vol 7 (2) ◽  
pp. 123
Author(s):  
K.C Woo ◽  
Mark Jokinen ◽  
D.T Canvin
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Reconstituted System ◽  
Spinach Leaves

A reconstituted system of supernatant and mitochondria from spinach leaves reduced NO3- in the presence of NAD+. A faster rate (2-6 times) of NO3- reduction was obtained when oxaloacetate (OAA) and glycine were present. The reduction of NO3- in the presence of OAA and glycine was sensitive to inhibition by n-butyl malonate, suggesting that the dicarboxylate exchange carrier was involved in the transport of malate out of the mitochondria. The capacity of the dicarboxylate shuttle to reduce NO,- was 63 % that of the in vitvo nitrate reductase activity in the supernatant

Differential effects of ozone on in vivo nitrate reduction in soybean cultivars. I. Response to exogenous sugars

1978 ◽  
Vol 56 (13) ◽  
pp. 1540-1544 ◽  
Author(s):  
Albert C. Purvis
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Foliar Injury ◽  
Glycolytic Intermediates ◽  
Glycine Max L ◽  
Growth Chambers ◽  
Visible Foliar Injury

Two cultivars of soybeans (Glycine max (L.) Merr.) differing widely in their resistance to ozone were exposed to 0.5 μl/ℓ ozone for 2 h in growth chambers. In vivo nitrate reduction was depressed by more than 50% in the primary leaves of Dare, the ozone-sensitive cultivar, but was not significantly altered in Hood, the ozone-resistant cultivar. Sucrose, up to 1.5% (w/v), added to excised seedlings of the Dare cultivar during exposure to ozone eliminated the ozone depression of in vivo nitrate reductase activity and also reduced foliar injury. Addition of two glycolytic intermediates, glyceraldehyde-3-phosphate and fructose-1,6-diphosphate, to the infiltration medium recovered some in vivo nitrate reduction in treated Dare leaves. The levels of extractable nitrate reductase and glyceraldehyde-3-phosphate dehydrogenase in the primary leaves of both cultivars were unaltered by ozone fumigations. These observations led to the conclusion that ozone depression of in vivo nitrate reduction is not due to ozone inactivation of nitrate reductase or of the enzymes coupling nitrate reduction to glycolysis, but may be caused by an inadequate supply of photosynthetic sugars. It was also noted that ozone depression of in vivo nitrate reduction only occurred with treatments which subsequently caused the development of visible foliar injury.

scholarly journals Respiratory Nitrate Ammonification by Shewanella oneidensis MR-1

2006 ◽  
Vol 189 (2) ◽  
pp. 656-662 ◽  
Author(s):  
Claribel Cruz-García ◽  
Alison E. Murray ◽  
Joel A. Klappenbach ◽  
Valley Stewart ◽  
James M. Tiedje
Keyword(s):  
Nitrous Oxide ◽  
Nitrate Reductase ◽  
Electron Acceptor ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Shewanella Oneidensis ◽  
Gene Encoding ◽  
Nitrate Ammonification ◽  
Sequential Reduction

ABSTRACT Anaerobic cultures of Shewanella oneidensis MR-1 grown with nitrate as the sole electron acceptor exhibited sequential reduction of nitrate to nitrite and then to ammonium. Little dinitrogen and nitrous oxide were detected, and no growth occurred on nitrous oxide. A mutant with the napA gene encoding periplasmic nitrate reductase deleted could not respire or assimilate nitrate and did not express nitrate reductase activity, confirming that the NapA enzyme is the sole nitrate reductase. Hence, S. oneidensis MR-1 conducts respiratory nitrate ammonification, also termed dissimilatory nitrate reduction to ammonium, but not respiratory denitrification.

Nitrate reductase activities of rhizobia and the correlation between nitrate reduction and nitrogen fixation

1979 ◽  
Vol 25 (10) ◽  
pp. 1169-1174 ◽  
Author(s):  
James R. Manhart ◽  
Peter P. Wong
Keyword(s):  
Nitrogen Fixation ◽  
Nitrate Reductase ◽  
Nitrate Reduction ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Root Nodules ◽  
Sole Source ◽  
Rhizobium Japonicum ◽  
Rhizobium Trifolii ◽  
Rhizobium Species

All species of Rhizobium except R. lupini had nitrate reductase activity. Only R. lupini was incapable of growth with nitrate as the sole source of nitrogen. However, the conditions necessary for the induction of nitrate reductase varied among species of Rhizobium. Rhizobium japonicum and some Rhizobium species of the cowpea strains expressed nitrate reductase activities both in the root nodules of appropriate leguminous hosts and when grown in the presence of nitrate. Rhizobium trifolii, R. phaseoli, and R. legnminosarum did not express nitrate reductase activities in the root nodules, but they did express them when grown in the presence of nitrate. In bacteroids of R. japonicum and some strains of cowpea Rhizobium, high N2 fixation activities were accompanied by high nitrate reductase activities. In bacteroids of R. trifolii, R. leguminosarum, and R. phaseoli, high N2 fixation activities were not accompanied by high nitrate reductase activities.

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