Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.7.1.2 (nitrate reductase)
3,861 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Synthesis of wild-type Neurospora crassa assimilatory nitrate reductase is induced in the presence of nitrate ions and repressed in the presence of ammonium ions. Effects of several Neurospora mutations on the regulation of this enzyme are shown: (i) the mutants, nit-1 and nit-3, involving separate lesions, lack reduced nicotinamide adenine dinucleotide (NADPH)-nitrate reductase activity and at least one of three other activities associated with the wild-type enzyme. The two mutants do not require the presence of nitrate for induction of their aberrant nitrate reductases and are constitutive for their component nitrate reductase activities in the absence of ammonium ions. (ii) An analog of the wild-type enzyme (similar to the nit-1 enzyme) is formed when wild type is grown in a medium in which molybdenum has been replaced by vanadium or tungsten; the resulting enzyme lacks NADPH-nitrate reductase activity. Unlike nit-1, wild type produced this analog only in the presence of nitrate. Contaminating nitrate does not appear to be responsible for the observed mutants' activities. Nitrate reductase is proposed to be autoregulated. (iii) Mutants (am) lacking NADPH-dependent glutamate dehydrogenase activity partially escape ammonium repression of nitrate reductase. The presence of nitrate is required for the enzyme's induction. (iv) A double mutant, nit-1 am-2, proved to be an ideal test system to study the repressive effects of nitrogen-containing metabolites on the induction of nitrate reductase activity. The double mutant does not require nitrate for induction of nitrate reductase, and synthesis of the enzyme is not repressed by the presence of high concentrations of ammonium ions. It is, however, repressed by the presence of any one of six amino acids. Nitrogen metabolites (other than ammonium) appear to be responsible for the mediation of "ammonium repression."
...
PMID:Induction and repression of nitrate reductase in Neurospora crassa. 14

The inhibition of the activity of xanthine oxidase by vanadate was strikingly similar to vanadate inhibition of another molybdoprotein nitrate reductase. Although the main catalytic activity of both enzymes was inhibited, the partial NADH oxidase activity associated with these enzymes was stimulated several fold. It appears that the metal ion binds at multiple site in both enzymes. In the absence of any enzymes a combination of vanadium (V) and molybdenum (V) in air was found to oxide NADH rapidly.
...
PMID:Effects of vanadate on the molybdoproteins xanthine oxidase and nitrate reductase: kinetic evidence for multiple site interaction. 689 79

Tungsten resistant (Wr) mutants of Het+Nif+Nia+, Het+Nif-Nia+ and Het+Nif+Nia- strains of Nostoc muscorum were isolated with severely defective molybdate transport activity. All such mutants showed vanadium (V)-dependent nitrogenase activity and/or nitrate reductase activity and V-dependent growth on N2-nitrogen and/or NO3(-)-nitrogen and V-dependent NO3(-)-repression of heterocyst formation and nitrogenase activity. None of them grew with molybdenum (Mo) under parallel growth condition. Results strongly suggest the ability of V to replace Mo in N2-assimilation or NO3(-)-assimilation under Mo-deficiency.
...
PMID:Mutational replacement of molybdenum by vanadium in assimilation of N2 or NO3- as nitrogen source in the cyanobacterium Nostoc muscorum. 833 16

We studied the effects of administrating the nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), or the nitric oxide precursor, L-arginine, on hemodynamic variables and serum nitrate concentrations in an anesthetized ovine model of endotoxemia to assess the effects on regional visceral blood flow and to determine whether L-arginine availability limits nitric oxide production. Animals received Escherichia coli endotoxin (2 micrograms/kg) followed 2 h later by L-NAME (25 mg/kg), L-arginine (0.575 g/kg), or saline administered over 1 h followed by an infusion of the same dose over 8 h (n = 6 per group). Renal and mesenteric blood flow were measured by placement of electromagnetic flow probes, and serum nitrate concentrations were determined using vanadium III chloride or nitrate reductase reduction to nitric oxide or nitrite, respectively. The results showed L-NAME significantly increased systemic vascular resistance (P < 0.01), decreased serum nitrate concentrations (P < 0.05), and caused a transient reduction in mesenteric blood flow (P < 0.05). L-Arginine caused a reduction in systemic vascular resistance (P < 0.01), increased mesenteric blood flow (P < 0.001) and conductance (P < 0.05). There were no significant changes in renal arterial blood flow in either group. We conclude that the availability of L-arginine limits nitric oxide production in endotoxemia and, furthermore, that L-arginine administration in this model causes significant mesenteric vasodilatation. L-NAME administration had only limited effect on visceral blood flow despite a marked increase in systemic vascular resistance and a reduction in nitric oxide production.
...
PMID:L-arginine augments nitric oxide production and mesenteric blood flow in ovine endotoxemia. 889 20

A spontaneous mutant derivative of Azotobacter vinelandii CA12 (delta nif HDK), which vanadium-dependent nitrogen fixation is not inhibited by molybdenum (A. vinelandii CARR), grows profusely on BNF-agar containing 1 microM Na2MoO4, alone or supplemented with 1 microM V2O5. The expression of A. vinelandii vnfH::lacZ and vnfA::lacZ fusions in A. vinelandii CARR was not inhibited by 1 mM Na2MoO4, whereas molybdenum at much lower concentration inhibited the expression of vnfH::lacZ and vnfA::lacZ fusions in A. vinlandii CA12. The mutant also exhibited normal acetylene reduction activity in the presence of 1 microM Na2MoO4. The expression of A. vinelandii nifH::lacZ fusion in A. vinelandii CARR was low even though the cells were cultured under non-repressing conditions with urea as nitrogen source in the presence of Na2MoO4. The molybdenum content of A. vinelandii CARR cells was found to be about one-fourth that of A. vinelandii CA12. No nitrate reductase activity could be detected in A. vinelandii CARR when the cells were cultured in the presence of 10 microM Na2MoO4, whereas A. vinelandii CA12 exhibited some activity even with 100 pM Na2MoO4.
...
PMID:Characterization of a spontaneous mutant of Azotobacter vinelandii in which vanadium-dependent nitrogen fixation is not inhibited by molybdenum. 959 78

Two catalytically distinct molybdenum-free dissimilatory nitrate reductases, a soluble periplasmic and a membrane-bound one, were isolated from the vanadate-reducing facultatively anaerobic bacterium Pseudomonas isachenkovii and purified to electrophoretic homogeneity. The enzymes did not contain molybdenum, the periplasmic enzyme contained vanadium, whereas the membrane-bound enzyme was vanadium-free. Both nitrate reductases lacked molybdenum cofactor. This fact was proved by reconstitution of the apoprotein of the nitrate reductase of Neurospora crassa nit-1 mutant. This is the first demonstration of molybdenum-free and molybdenum cofactor-free nitrate reductases.
...
PMID:Molybdenum-free nitrate reductases from vanadate-reducing bacteria. 988 95

Numerous methods are available for measurement of nitrate (NO(-)(3)). However, these assays can either be time consuming or require specialized equipment (e.g., nitrate reductase, chemiluminescent detector). We have developed a method for simultaneous evaluation of nitrate and nitrite concentrations in a microtiter plate format. The principle of this assay is reduction of nitrate by vanadium(III) combined with detection by the acidic Griess reaction. This assay is sensitive to 0.5 microM NO(-)(3) and is useful in a variety of fluids including cell culture media, serum, and plasma. S-Nitrosothiols and L-arginine derivatives were found to be potential interfering agents. However, these compounds are generally minor constituents of biological fluids relative to the concentration of nitrate/nitrite. This report introduces a new, convenient assay for the stable oxidation products of nitrogen oxide chemistry in biological samples.
...
PMID:A rapid, simple spectrophotometric method for simultaneous detection of nitrate and nitrite. 1600 57

A novel molybdenum-free nitrate reductase was isolated from the obligate chemolithoautotrophic and facultative anaerobic, (halo)alkaliphilic sulphur-oxidizing bacterium Thioalkalivibrio nitratireducens strain ALEN 2. The enzyme was found to contain vanadium and haem c as cofactors. Its native molecular mass was determined as 195 kDa, and the enzyme consists of four identical subunits with apparent molecular masses of 57 kDa. Apart from nitrate, the enzyme can utilize nitrite, chlorate, bromate, selenate and sulphite as electron acceptors. Moreover, it also has a haloperoxidase activity.
...
PMID:New enzyme belonging to the family of molybdenum-free nitrate reductases. 1223 51

As measured 7, 14, and 21 days after the application of 10(-2) M vanadyl sulfate solution to the foliage of 4.5-month-old sugar beet plants, significantly less growth of the leaves and an increase in the sucrose content of the storage root resulted. Accompanying these alterations were a higher rate of carbon dioxide fixation, a lower rate of respiration, and a decreased rate of nitrate reductase, glutamic-pyruvic transaminase, phosphatase, and invertase activity. The enzymes of sucrose synthesis, sucrose synthetase, sucrose phosphate synthetase and uridine diphosphate glucose-pyrophosphorylase were stimulated. The content of reducing sugar, nitrite N, amino acids and protein was less, and that of nitrate N was greater in the vanadium-treated plants. In the majority of cases the greatest magnitude of change occurred during the first 7 days following treatment. The changes in growth and chemical composition are believed to be closely related to the stimulation or inhibition of the various enzymes by vanadyl sulfate.
...
PMID:Effect of Vanadium on Growth, Chemical Composition, and Metabolic Processes of Mature Sugar Beet (Beta vulgaris L.) Plants. 1665 5

The two predominant forms of vanadium occurring in the geo-, aqua- and biosphere, soluble vanadate(V) and insoluble oxovanadium(IV) (vanadyl), are subject to bacterial activity and transformation. Bacteria belonging to genera such as Shewanella, Pseudomonas and Geobacter can use vanadate as a primary electron acceptor in dissimilation or respiration, an important issue in the context of biomineralisation and soil detoxification. Azotobacter, which can employ vanadium as an essential element in nitrogen fixation, secretes a vanadophore which enables the uptake of vanadium(V). Siderophores secreted by other bacteria competitively (to ferric iron) take up vanadyl and thus interfere with iron supply, resulting in bacteriostasis. The halo-alkaliphilic Thioalkalivibrio nitratireducens possibly uses vanadium as a constituent of an alternative, molybdopterin-free nitrate reductase. Marine macro-algae can generate a variety of halogenated organic compounds by use of vanadate-dependent haloperoxidases, and a molecular vanadium compound, amavadin, from Amanita mushrooms has turned out to be an efficient catalyst in oxidation reactions. The present account is a focused and critical review of the current knowledge of the interplay of bacteria and other primitive forms of life (cyanobacteria, algae, fungi and lichens) with vanadium, with the aim to provide perspectives for applications and further investigations.
...
PMID:Is vanadium a more versatile target in the activity of primordial life forms than hitherto anticipated? 1832 16


1 2 Next >>

---