scholarly journals Oxidation–reduction potentials of molybdenum and iron–sulphur centres in nitrate reductase from Escherichia coli

1979 ◽  
Vol 177 (2) ◽  
pp. 757-759 ◽  
Author(s):  
S P Vincent
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Escherichia Coli K12 ◽  
Reduction Potentials ◽  
Oxidation Reduction

The potentials of the couples Mo(IV)–(Mo(V) and Mo(V)–Mo(VI) in nitrate reductase from Escherichia coli K12 were measured as + 180 mV and + 220 mV respectively at pH 7.14. The potentials associated with two other e.p.r. signals, believed to be due to iron–sulphur centres, were measured as + 50 mV and + 80 mV.

scholarly journals Biochemical and immunological evidence for a second nitrate reductase in Escherichia coli K12

1987 ◽  
Vol 168 (2) ◽  
pp. 451-459 ◽  
Author(s):  
Chantal IOBBI ◽  
Claire-Lise SANTINI ◽  
Violaine BONNEFOY ◽  
Gerard GIORDANO
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Escherichia Coli K12

scholarly journals Electron-paramagnetic-resonance studies on nitrate reductase from Escherichia coli K12

1978 ◽  
Vol 171 (3) ◽  
pp. 639-647 ◽  
Author(s):  
Stephen P. Vincent ◽  
Robert C. Bray
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Extraction Procedure ◽  
Hydrophobic Interaction Chromatography ◽  
Low Ph ◽  
Paramagnetic Resonance ◽  
Escherichia Coli K12 ◽  
Exchangeable Proton ◽  
Ph Range ◽  
Nitrate And Nitrite

Nitrate reductase was purified from anaerobically grown Escherichia coli K12 by a method based on the Triton X-100 extraction procedure of Clegg[(1976) Biochem. J.153, 533–541], but hydrophobic interaction chromatography was used in the final stage. E.p.r. spectra obtained from the enzyme under a variety of conditions are well resolved and were interpreted with the help of the computer-simulation procedures of Lowe [(1978) Biochem. J.171, 649–651]. Parameters for five molybdenum(V) species from the enzyme are given. The low-pH species (gav. 1.9827) is in pH-dependent equilibrium with the high-pH species (gav. 1.9762), the pK for interconversion of the species being 8.26. Of a variety of anions tested, only nitrate and nitrite formed complexes with the enzyme (in the low-pH form), giving modified molybdenum(V) e.p.r. spectra. These complexes, as well as the low-pH form of the free enzyme, showed interaction of molybdenum with a single exchangeable proton. The fifth molybdenum(V) species, sometimes detected in small amounts, appears not to be due to functional nitrate reductase. After full reduction of the enzyme with dithionite, addition of nitrate caused reoxidation of molybdenum to the quinquivalent state, in a time less than the enzyme turnover. Activity of the enzyme in the pH range 6–10 is controlled by a pK of 8.2. It is suggested that the low-pH signal-giving species is the form of the enzyme involved in the catalytic cycle. Iron–sulphur and other e.p.r. signals from the enzyme are briefly described and the enzymic reaction mechanism is discussed.

Genetic mapping of the chl C gene of the nitrate reductase a system in Escherichia coli K12

1969 ◽  
Vol 35 (5) ◽  
pp. 659-662 ◽  
Author(s):  
Juan Puig ◽  
Edgard Azoulay ◽  
Francis Pichinoty ◽  
Jacqueline Gendre
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Genetic Mapping ◽  
Escherichia Coli K12

scholarly journals Purification and further characterization of the second nitrate reductase of Escherichia coli K12

1990 ◽  
Vol 188 (3) ◽  
pp. 679-687 ◽  
Author(s):  
Chantal IOBBI-NIVOL ◽  
Claire-Lise SANTINI ◽  
Francis BLASCO ◽  
Gerard GIORDANO
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Escherichia Coli K12

scholarly journals Purification and some properties of nitrate reductase (EC 1.7.99.4) from Escherichia coli K12

1976 ◽  
Vol 153 (3) ◽  
pp. 533-541 ◽  
Author(s):  
R A Clegg
Keyword(s):  
Escherichia Coli ◽  
Aqueous Solution ◽  
Nitrate Reductase ◽  
Cell Envelope ◽  
Purification Procedure ◽  
Benzyl Viologen ◽  
Escherichia Coli K12 ◽  
Enzyme Subunits ◽  
Triton X

1. Nitrate reductase was purified 134-fold from Escherichia coli K12. The purification procedure involves the release by Triton X-100 of the enzyme from the cell envelope. i. The purified enzyme exists in aqueous solution either as a monomer (mol. wt. about 220 000) or as an associated form (probably a tetramer; mol.wt. about 880 000). 3. The purified enzyme has three subunits with apparent mol.wts. of 150 000, 67000 and 65000. An additional subunit of apparent mol.wt. 20000 is present in a haem-containing fraction that is also produced by the preparative procedure described. 4. None of the enzyme subunits is present in the cell envelope of cells grown in the absence of nitrate. 5. Reversible changes in the activity of nitrate reductase in vitro with FMNH2 as reductant can be induced under circumstances which are without effect on the reduced Benzyl Viologen-NO3-activity.

scholarly journals Characterization and phenotypic control of the cytochrome content of Escherichia coli

1979 ◽  
Vol 182 (2) ◽  
pp. 465-472 ◽  
Author(s):  
Graeme A. Reid ◽  
W. John Ingledew
Keyword(s):  
Escherichia Coli ◽  
Electron Transport ◽  
Cytochrome B ◽  
Terminal Electron Acceptor ◽  
E Coli ◽  
Reduction Potentials ◽  
Electrode Potentials ◽  
Point Potential ◽  
Oxidation Reduction ◽  
Cytochrome D

1. Electron-transport particles derived from Escherichia coli grown aerobically contain three b-type cytochromes with mid-point oxidation–reduction potentials at pH7 of +260mV, +80mV and −50mV, with n=1 for each. The variation of these values with pH was determined. 2. E. coli develops a different set of b-type cytochromes when grown anaerobically on glycerol with fumarate or nitrate as terminal electron acceptor. Electron-transport particles of fumarate-grown cells contain b-type cytochromes with mid-point potentials at pH7 of +140mV and +250mV (n=1). These two cytochromes are also present in cells grown with nitrate as terminal acceptor, where an additional cytochrome b with a mid-point potential of +10mV (n=1) is developed. 3. The wavelengths of the α-absorption-band maxima of the b-type cytochromes at 77K were: (a) for aerobically grown cells, cytochrome b (Em7 +260mV), 556nm and 563nm, cytochrome b (Em7 +80mV), 556nm and cytochrome b (Em7−50mV), 558nm; (b) for anaerobically grown cells, cytochrome b (Em7 +250mV), 558nm, cytochrome b (Em7 +40mV), 555nm and cytochrome b (Em7 +10mV), 556nm. 4. Cytochrome d was found to have a mid-point potential at pH7 of +280mV (n=1). 5. Cytochrome a1 was resolved as two components of equal magnitude with mid-point potentials of +260mV and +160mV (n=1). 6. Redox titrations performed in the presence of CO showed that one of the b-type cytochromes in the aerobically grown cultures was reduced, even at the upper limits of our range of electrode potentials (above +400mV). Cytochrome d was also not oxidizable in the presence of CO. Neither of the cytochromes a1 was affected by the presence of CO.

scholarly journals Characterization of the membrane-bound nitrate reductase activity of aerobically grown chlorate-sensitive mutants of escherichia coli K12

FEBS Letters ◽  
1978 ◽  
Vol 95 (2) ◽  
pp. 290-294 ◽  
Author(s):  
Gérard Giordano ◽  
Alec Graham ◽  
David H. Boxer ◽  
Bruce A. Haddock ◽  
Edgard Azoulay
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Escherichia Coli K12 ◽  
Membrane Bound
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