Biochemical characterization of the molybdenum cofactor mutants of Neurospora crassa: in vivo and in vitro reconstitution of NADPH-nitrate reductase activity

1984 ◽  
Vol 8 (8) ◽  
pp. 581-588 ◽  
Author(s):  
Nigel Stuart Dunn-Coleman
Keyword(s):  
Nitrate Reductase ◽  
Neurospora Crassa ◽  
Nitrate Reductase Activity ◽  
Biochemical Characterization ◽  
Reductase Activity ◽  
Molybdenum Cofactor ◽  
In Vitro Reconstitution

scholarly journals Biochemical Characterization of Molybdenum Cofactor-free Nitrate Reductase from Neurospora crassa

2013 ◽  
Vol 288 (20) ◽  
pp. 14657-14671 ◽  
Author(s):  
Phillip Ringel ◽  
Joern Krausze ◽  
Joop van den Heuvel ◽  
Ute Curth ◽  
Antonio J. Pierik ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Neurospora Crassa ◽  
Biochemical Characterization ◽  
Nitrate Assimilation ◽  
Molybdenum Cofactor ◽  
Site Formation ◽  
Epr Spectrum ◽  
Redox Active

Nitrate reductase (NR) is a complex molybdenum cofactor (Moco)-dependent homodimeric metalloenzyme that is vitally important for autotrophic organism as it catalyzes the first and rate-limiting step of nitrate assimilation. Beside Moco, eukaryotic NR also binds FAD and heme as additional redox active cofactors, and these are involved in electron transfer from NAD(P)H to the enzyme molybdenum center where reduction of nitrate to nitrite takes place. We report the first biochemical characterization of a Moco-free eukaryotic NR from the fungus Neurospora crassa, documenting that Moco is necessary and sufficient to induce dimer formation. The molybdenum center of NR reconstituted in vitro from apo-NR and Moco showed an EPR spectrum identical to holo-NR. Analysis of mutants unable to bind heme or FAD revealed that insertion of Moco into NR occurs independent from the insertion of any other NR redox cofactor. Furthermore, we showed that at least in vitro the active site formation of NR is an autonomous process.

Changes in Leaf Nitrate Reductase Activity In Vivo and In Vitro During Light-Dark Transitions

1999 ◽  
Vol 8 (1) ◽  
pp. 37-40 ◽  
Author(s):  
B. K. Salalkar ◽  
R. S. Shaikh ◽  
R. M. Naik ◽  
S. V. Munjal ◽  
B. B. Desai ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Leaf Nitrate

scholarly journals Effect of lead on nitrate reductase activity and nitrate assimilation in pea leaves

2014 ◽  
Vol 57 (4) ◽  
pp. 457-463 ◽  
Author(s):  
S. K. Sinha ◽  
H. S. Srivastava ◽  
S. N. Mishra
Keyword(s):  
Enzyme Activity ◽  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Organic Nitrogen ◽  
Reductase Activity ◽  
Total Organic Nitrogen ◽  
Intact Leaf ◽  
Leaf Tissues

The effect of Pb on nitrate reductase activity, protein, total organic nitrogen and on the chlorophyll content in excised and intact leaf tissues of <em>Pisum sativum</em> was examine. Enzyme activity assayed in vitro or in vivo in the excised leaves showed marked increase at lower concentrations of Pb while being inhibited at higher concentrations. In intact leaf tissues, the enzyme activity (in vivo or in vitro) was unaffected at lower concentrations but was inhibited at higher concentrations of Pb. Chlorophyll, carotenoids (non-nitrogenous pigments), soluble protein and organic nitrogen contents remained almost unaffected at all concentrations of Pb tested. It seems that nitrate reductase has a different response towards Pb pollution in this species, which is more tolerant to heavy metal pollution, especially Pb.

Effects of Glufosinate on Anion Uptake in Lemna gibba G 1

1989 ◽  
Vol 44 (1-2) ◽  
pp. 33-38 ◽  
Author(s):  
Gudrun D. Trogisch ◽  
Helmut Köcher ◽  
Wolfram R. Ullrich
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Nitrate Uptake ◽  
Dark Respiration ◽  
Reductase Activity ◽  
Lemna Gibba ◽  
Proton Cotransport ◽  
Chlorophyll Formation

Abstract The duckweed Lemna gibba G 1 was used as a model to study inhibitory sites with the herbicide and glutamate analogue glufosinate (PPT). Growth and chlorophyll formation were partly inhibited by 25 n-M, completely suppressed by 250 (im PPT. Photosynthesis showed partial inhibition within few hours, dark respiration ( 0 2 consumption) increased already within one hour. In the presence of 1 mM PPT in the light, the ammonium pool of Lemna increased to 600% within few hours, later to 1000%. The overall amino acid pool exhibited a slower increase to 300%, the nitrate pool only a slight increase, while total phosphate remained almost unchanged. In the dark all these effects were less pronounced than in the light. Nitrate, nitrite and phosphate uptake were partially inhibited by PPT, especially after 19 h PPT pretreatment. Nitrate reductase activity in vitro, after PPT treatment in vivo, showed an inhibition similar to that of nitrate uptake. Ammonium was not taken up but released under the same conditions. The data are explained by a combined effect of PPT, by inhibition of glutamine synthetase leading to accumulation of ammonium from photorespiration and proteolysis, by membrane depolarization and inhibition of anion/proton cotransport, by secondary uncoupling of phosphorylation, and by secondary inhibition of nitrate reductase activity.

Sign in / Sign up

Export Citation Format

Share Document