Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.7.1.4 (nitrite reductase)
 1,847 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The dye-linked methanol dehydrogenase from Paracoccus denitrificans grown aerobically on methanol has been purified and its properties compared with similar enzymes from other bacteria. It was shown to be specific and to have high affinity for primary alcohols and formaldehyde as substrate, ammonia was the best activator and the enzyme could be linked to reduction of phenazine methosulphate. 2. Paracoccus denitrificans could be grown anaerobically on methanol, using nitrate or nitrite as electron acceptor. The methanol dehydrogenase synthesized under these conditions could not be differentiated from the aerobically-synthesized enzyme. 3. Activities of methanol dehydrogenase, formaldehyde dehydrogenase, formate dehydrogenase, nitrate reductase and nitrite reductase were measured under aerobic and anaerobic growth conditions. 4. Difference spectra of reduced and oxidized cytochromes in membrane and supernatant fractions of methanol-grown P. denitrificans were measured. 5. From the results of the spectral and enzymatic analyses it has been suggested that anaerobic growth on methanol/nitrate is made possible by reduction of nitrate to nitrite using electrons derived from the pyridine nucleotide-linked dehydrogenations of formaldehyde and formate, the nitrite so produced then functioning as electron acceptor for methanol dehydrogenase via cytochrome c and nitrite reductase.
 ...
PMID:Aerobic and anaerobic growth of Paracoccus denitrificans on methanol. 71 72

Transient state, burst and steady state kinetics of reactions of the blue copper nitrite reductase (NIR) and blue copper protein from Achromobacter cycloclastes are investigated. The two copper-containing species are reacted with each other and where possible with dithionite, ascorbate and nitrite. Both copper proteins are fully reduced by dithionite with both S2O4(2-) and SO2-. species active. NIR is only partially reduced by ascorbate in an unusual biphasic reaction consistent with complete reduction of type-one copper followed by partial reduction of type-two copper. The rate of reduction of the type-one copper is accelerated using phenazine methosulfate as mediator. Nitrite can oxidize dithionite-reduced NIR but cannot reduce oxidized NIR. Rate constants were determined for all observed reactions.
 ...
PMID:Kinetic studies of the copper nitrite reductase from Achromobacter cycloclastes and its interaction with a blue copper protein. 359 51

Pseudomonas aureofaciens truncates the respiratory reduction of nitrate (denitrification) at the level of N2O. The nitrite reductase from this organism was purified to apparent electrophoretic homogeneity and found to be a blue copper protein. The enzyme contained 2 atoms of copper/85 kDa, both detectable by electron paramagnetic resonance (EPR) spectroscopy. The protein was dimeric, with subunits of identical size (40 +/- 3 kDa). Its pI was 6.05. The EPR spectrum showed an axial signal g at 2.21(8) and g at 2.04(5). The magnitude of the hyperfine splitting (A parallel = 6.36 mT) indicated the presence of type 1 copper only. The electronic spectrum had maxima at 280 nm, 474 nm and 595 nm (epsilon = 7.0 mM-1 cm-1), and a broad shoulder around 780 nm. A copper protein of low molecular mass (15 kDa), with properties similar to azurin, was also isolated from P. aureofaciens. The electronic spectrum of this protein showed a maximum at 624 nm in the visible range (epsilon = 2.5 mM-1 cm-1) and pronounced structures in the ultraviolet region. The EPR parameters were g parallel = 2.26(6) and g perpendicular = 2.05(6), with A parallel = 5.8 mT. The reduced azurin transferred electrons efficiently to nitrite reductase; the product of nitrite reduction was nitric oxide. The specific nitrite-reducing activity with ascorbate-reduced phenazine methosulfate as electron donor was 1 mumol substrate min-1 mg protein-1. The reaction product again was nitric oxide. Nitrous oxide was the reaction product from hydroxylamine and nitrite and from dithionite-reduced methyl viologen and nitrite. No 'oxidase' activity could be demonstrated for the enzyme. Our data disprove the presumed exclusiveness of cytochrome cd1 as nitrite reductase within the genus Pseudomonas.
 ...
PMID:Type 1, blue copper proteins constitute a respiratory nitrite-reducing system in Pseudomonas aureofaciens. 366 26

Methyl viologen and phenazine methosulfate (photosystem I electron acceptors), 3-(3,4-dichlorophenyl)-1, 1-dimethylurea (DCMU, electron-transport inhibitor), and methylamine (photophosphorylation uncoupler) were used to study the dependence of nitrite reduction on electron transport in chloroplasts.DCMU, methyl viologen, and phenazine methosulfate markedly inhibited, whereas methylamine stimulated NO(2) (-) reduction in isolated, intact spinach (Spinacia oleracea L.) chloroplasts. The addition of DCMU to leaf sections of spinach and corn, (Zea mays L. var. XL81), incubated with No(3) (-), caused no inhibition of nitrate reduction but inhibited nitrite reduction leading to the accumulation of NO(2) (-) in the light. The addition of methylamine to comparable leaf sections did not affect either nitrate or nitrite reduction.WE CONCLUDED THAT: (a) nitrite reduction is functionally associated with the electron transport arising from the light reactions of the chloroplast and this provides additional support for the localization of nitrite reductase in the chloroplast; (b) nitrite reduction is associated with photosystem I and ferredoxin is the most likely donor in leaf tissue; and (c) ATP is not involved directly in nitrite reduction. However, ATP synthesis, by regulating electron flow to photosystem I, can affect nitrite reduction in the light.
 ...
PMID:Dependence of nitrite reduction on electron transport chloroplasts. 1665 12