scholarly journals Oxidation–reduction midpoint potentials of the flavin, haem and Mo-pterin centres in spinach (Spinacia oleracea L.) nitrate reductase

1989 ◽  
Vol 263 (1) ◽  
pp. 285-287 ◽  
Author(s):  
C J Kay ◽  
M J Barber ◽  
B A Notton ◽  
L P Solomonson
Keyword(s):  
Nitrate Reductase ◽  
Room Temperature ◽  
Spinacia Oleracea ◽  
Midpoint Potential ◽  
Redox Couples ◽  
Oxidation Reduction ◽  
Spinacia Oleracea L ◽  
Unicellular Green Alga ◽  
Green Alga Chlorella ◽  
Prosthetic Groups

Oxidation-reduction midpoint potentials have been determined for the flavin, cytochrome b557 and Mo-pterin prosthetic groups of spinach (Spinacia oleracea L.) assimilatory nitrate reductase using visible, c.d. and room-temperature e.p.r. potentiometric titrations. At pH 7 and 25 degrees C, the midpoint potential for the FAD/FADH2 couple was determined by c.d. potentiometry to be -280 +/- 10 mV (n = 2). The redox potential for reduction of the haem was determined by visible potentiometry to be -123 +/- 10 mV (n = 1), significantly lower than the previously published value of -60 mV [Fido, Hewitt, Notton, Jones & Nasrulhaq-Boyce (1979) FEBS Lett. 99, 180-182]. Potentials for the Mo(VI)/Mo(V) and Mo(V)/Mo(IV) redox couples, determined by room-temperature e.p.r. potentiometry, were found to be +2 +/- 20 and -6 +/- 20 mV respectively. These values are very similar to the values previously determined for the FAD, haem and Mo-pterin centres in assimilatory nitrate reductase isolated from the unicellular green alga Chlorella vulgaris and indicate a close thermodynamic similarity between the two enzymes.

Effect of Biochar on Microorganisms Quantity and Soil Physicochemical Property in Rhizosphere of Spinach (Spinacia oleracea L.)

2013 ◽  
Vol 295-298 ◽  
pp. 210-219 ◽  
Author(s):  
Guang Ming Han ◽  
Jun Meng ◽  
Wei Ming Zhang ◽  
Wen Fu Chen
Keyword(s):  
Spinacia Oleracea ◽  
Chemical Properties ◽  
Nutrient Content ◽  
Denitrifying Bacteria ◽  
Total Carbon ◽  
Mineral Nutrient ◽  
Microbial Biomass C ◽  
Greenhouse Soil ◽  
Oxidation Reduction ◽  
Spinacia Oleracea L

To investigate the effects of biochar on greenhouse soil, three biochar treatments, i.e. 0 t ha-1 (C0), 12.5 t ha-1 (C1) and 25 t ha-1 (C2), were applied to the rhizosphere of spinach (Spinacia oleracea L.). And the microbial biomass C (MBC), the quantities of the bacteria, fungi, actinomyces, ammonifying bacteria, azotobacter and denitrifying bacteria, pH, oxidation-reduction potential (Eh), and mineral nutrient content were studied. The results indicated that MBC contents with C2 and C1 treatments were significantly (P＜0.01) higher than those with C0 treatment, and the quantities of bacteria, fungi, actinomyces, ammonifying bacteria, azotobacter, and denitrifying bacteria under C1 treatment were 1.06 fold, 2.18 fold, 1.17 fold, 1.47 fold, 2.94 fold and 0.38 fold of those with C0 treatment in rhizosphere of spinach, while those with C2 treatment were 1.25 fold, 2.08 fold, 1.24 fold, 1.41 fold, 4.92 fold and 1.76 fold of those with C0 treatment. The total phosphorus, total carbon, total sulphur, total potassium content, carbon/nitrogen, and Eh with C2 and C1 treatments were higher than in those with C0 treatment. Our results suggest that biochar can be used as ameliorant to improve quantity of microorganisms and physical and chemical properties of greenhouse soil.

scholarly journals Red-Light Effects Sensitized by Methylene Blue on Nitrate Reductase from Spinach (Spinacia oleracea L.) Leaves

1984 ◽  
Vol 39 (11-12) ◽  
pp. 1079-1084 ◽  
Author(s):  
S. G. Mauriño ◽  
M. A. Vargas ◽  
P. J. Aparicio ◽  
J. M. Maldonado
Keyword(s):  
Methylene Blue ◽  
Nitrate Reductase ◽  
Spinacia Oleracea ◽  
Red Light ◽  
Deuterated Water ◽  
Anaerobic Conditions ◽  
Molybdenum Complex ◽  
Spinacia Oleracea L ◽  
Light Effects

Abstract Nitrate reductase from spinach (Spinacia oleracea L.) leaves, which had been inactivated in vitro by incubation with NADH and cyanide, was fully reactivated in minutes when irradiated in anaerobic conditions with red light in the presence of methylene blue. Both the rate and the extent of reactivation increased with light intensity (6 to 100 W·m-2) and dye concentration (1 to 10 μM). On the contrary, photoreactivation was completely abolished when NADH or ethylenediaminetetra-acetic acid were present during irradiation. We propose that methylene blue, when photo excited, exhibits a redox potential positive enough to reoxidise the CN--re-duced molybdenum complex settled in the inactive enzyme, thus causing its reactivation. On the other hand, prolonged irradiation of nitrate reductase, under air and in the presence of methylene blue, promoted an oxygen-dependent irreversible inactivation of the two partial activities of the enzyme. This inactivation was markedly enhanced in 77% deuterated water and greatly prevented by azide, which indicates that singlet oxygen is the species primarily involved in the photooxidative inactivation of the enzyme.

scholarly journals Spectroscopic, thermodynamic and kinetic properties of Candida nitratophila nitrate reductase

1990 ◽  
Vol 272 (2) ◽  
pp. 545-548 ◽  
Author(s):  
C J Kay ◽  
M J Barber ◽  
L P Solomonson ◽  
D Kau ◽  
A C Cannons ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Nitrate Reductase ◽  
Chlorella Vulgaris ◽  
Close Similarity ◽  
Kinetic Properties ◽  
Potentiometric Titrations ◽  
Oxidation Reduction ◽  
Visible Spectra ◽  
Rate Limiting ◽  
Prosthetic Groups

Visible spectra of oxidized and reduced Candida nitratophila assimilatory NAD(P)H:nitrate reductase yielded absorbance maxima of 413 nm and 423 nm, and 525 nm and 555 nm respectively, characteristic of a b5-type cytochrome. E.p.r. spectra of the partially reduced enzyme revealed a single Mo(V) species (g1 = 1.9957, g2 = 1.9664 and g3 = 1.9658) exhibiting superhyperfine coupling to a single proton [A(1H)av. = 1.4 mT]. Oxidation-reduction midpoint potentials (E'0) (25 degrees C, pH 7) for the haem and Mo-pterin prosthetic groups were determined by visible and e.p.r. potentiometric titrations and yielded values of E'0 = -174 mV (n = 1) for the haem and E'0 = -3 mV and E'0 = -27 mV for the Mo(VI)/Mo(V) and Mo(V)/Mo(IV) couples respectively. Comparison of initial rates of the NADH-oxidizing and nitrate-reducing partial activities at various ionic strengths indicated electron transfer from reduced haem to Mo was rate-limiting during turnover. These results suggest a close similarity between Candida nitratophila and Chlorella vulgaris nitrate reductases.

Cloning of a nitrate reductase inactivator (NRI) cDNA from Spinacia oleracea L. and expression of mRNA and protein of NRI in cultured spinach cells

Planta ◽  
2003 ◽  
Vol 216 (6) ◽  
pp. 961-968 ◽  
Author(s):  
Masatoshi Sonoda ◽  
Hiroaki Ide ◽  
Shinya Nakayama ◽  
Asako Sasaki ◽  
Shinei Kitazaki ◽  
...  
Keyword(s):  
Nitrate Reductase ◽  
Spinacia Oleracea ◽  
Spinacia Oleracea L ◽  
Nitrate Reductase Inactivator

Sequence Analysis of Cloned cDNA and Proteolytic Fragments for Nitrate Reductase from Spinacia oleracea L.

1991 ◽  
Vol 32 (7) ◽  
pp. 1031-1038 ◽  
Author(s):  
Naomasa Shiraishi ◽  
Yoshihiro Kubo ◽  
Go Takeba ◽  
Seiichiro Kiyota ◽  
Katsuhiro Sakano ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Nitrate Reductase ◽  
Spinacia Oleracea ◽  
Spinacia Oleracea L ◽  
Cloned Cdna
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