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Showing papers on "Nitrite published in 1979"


Journal ArticleDOI
TL;DR: In this paper, the flow injection principle is used in the photometric determination of nitrite and nitrate with sulfanilamide and N-(1-naphthyl)ethylenediamine as reagents.

230 citations


Journal ArticleDOI
TL;DR: The present results are consistent with a mechanism of NH2OH oxidation in which the oxidation of an intermediate compound of the oxidation state of (HNO) occurs by dehydrogenation rather than direct addition of O.

226 citations


Journal ArticleDOI
TL;DR: In this article, a technique for detection and measurement of NO x emissions from soybean plants was described, and the technique was used to detect free nitrite accumulations and plant metabolites.

214 citations



Journal ArticleDOI
TL;DR: In this paper, a fourteen-step reaction scheme was proposed for photolysis of low-nitrate seawater and the primary products were the free radicals NO and OH, with a suggested global average for comparison purposes of 1 −10·103 moles m−2yr−1.

192 citations


Journal ArticleDOI
TL;DR: In this article, the authors reported significant differences in nutrient concentrations associated with marine snow from those of the surrounding water, in eight sets of nutrient measurements, ammonia was more concentrated in aggregates in seven sets, nitrite in three sets, and nitrate in one set.
Abstract: Measurements of ammonia, nitrite, nitrate, and phosphate indicate significant differences in nutrient concentrations associated with marine snow from those of the surrounding water, In eight sets of nutrient measurements, ammonia was more concentrated in aggregates in seven sets, nitrite in three sets, and nitrate in one set, Phosphate was more concentrated in one set, but less concentrated in three sets. Aggregates represent nutrient micropatches ranging in size from

192 citations


Journal ArticleDOI
TL;DR: The soluble fraction prepared from crude cell extracts oxidized hydroquinone to a product whose spectral properties were identical to those reported for γ-hydroxymuconic semialdehyde.

143 citations


Journal ArticleDOI
TL;DR: In this article, the concentration of residual nitrite, nitrate, oxygen, and methemoglobin (Hb+) was determined successively during the reaction of oxyhemoglobin with nitrite.

137 citations


Journal ArticleDOI
TL;DR: Sorbate, especially in combination with nitrite at concentrations adequate only for cured meat color and flavor development, is at least as effective as currently used nitrite levels in delaying C. botulinum growth and toxin production.

127 citations


Journal ArticleDOI
TL;DR: EPR spectroscopic and chemical analyses of spinach nitrite reductase show that the enzyme contains one reducible iron-sulfur center, and one site for binding either cyanide or nitrite, per siroheme, indicating a role for the Fe4S4 center in catalysis.

111 citations


Journal ArticleDOI
TL;DR: Channel catfish fingerlings exposed to 1.0, 2.5, and 5.0 mg/L nitrite for 5 h developed 42.5 ± 3.8% methemoglobin, which is close to normal for channel catfish exposed to nitrite, and when transferred to water containing 5 µm nitrite and 250‵m sodium chloride, meethemoglobin levels returned to normal within 24’h.
Abstract: Exposure of channel catfish (Ictalurus punctatus) fingerlings for 24 h to 1.0, 2.5, and 5.0 mg/L nitrite (pH = 7; hardness = 40 mg/L; temperature = 22–25 °C) produced methemoglobin levels of 20.7 ± 1.9%, 59.8 ± 1.9%, and 77.4 ± 1.4% (SE), respectively. However, methemoglobin levels were not elevated when fish were simultaneously exposed to 1.0, 2.5, and 5.0 mg/L nitrite and 25, 50, and 100 mg/L sodium chloride, respectively. Acclimation to sodium chloride for 24 h before exposure to nitrite did not enhance the inhibitory action of sodium chloride. Fish exposed to 5 mg/L nitrite for 5 h developed 42.5 ± 3.8% methemoglobin. When transferred to water containing 5 mg/L nitrite and 250 mg/L sodium chloride, methemoglobin levels returned to normal within 24 h. Environmental chloride probably inhibits methemoglobin formation by competing with nitrite for entrance into the gills of the fish. An ionic ratio of 16 Cl− to 1 NO2− is capable of complete suppression of nitrite-induced methemoglobin formation. Bicarbona...

01 Jan 1979
TL;DR: The chemistry of nitrite, the properties of meat, and the curing process are covered in this review of the reactions of Nitrite in meat as mentioned in this paper. But, it is worth noting that only 50% of the nitrite added to the cured meat can be analyzed chemically after completion of processing.
Abstract: The chemistry of nitrite, the properties of meat, and the curing process are covered in this review of the reactions of nitrite in meat. The salts of nitrite are soluble in water and very reactive. Meat contains an enormous variety of chemicals and these chemicals are contained in a complicated morphological muscle structure. When nitrite is added to meat for curing, less than 50% of that added can be analyzed chemically after completion of processing. Nitrite reacts with the myoglobin to form the cured meat color. Nitrite also reacts with the proteins, lipids and carbohydrates in the meat or its additives. Before heating, some of the nitrite of cured beef often turns into nitrate, in some cases up to 40%. Research is being conducted to block the formation of nitrosamines in cured meat

Journal ArticleDOI
TL;DR: Nitrite was shown to inhibit active transport, oxygen uptake, and oxidative phosphorylation by Pseudomonas aeruginosa, and the evidence strongly suggested that nitrite exerted its inhibitory effect by oxidizing ferrous iron of an electron carrier(s), such as cytochrome oxidase, to ferric iron.
Abstract: Nitrite was shown to inhibit active transport, oxygen uptake, and oxidative phosphorylation byPseudomonas aeruginosa. The evidence strongly suggested that nitrite exerted its inhibitory effect by oxidizing ferrous iron of an electron carrier(s), such as cytochrome oxidase, to ferric iron. The inhibitory effect of nitrite was readily reversible by washing the cells. Glucose transport byStreptococcus faecalis andS. lactis was not inhibited by nitrite, presumably because these species lack cytochromes and because glucose is transported by the phosphoenolpyruvate: phosphotransferase system rather than by active transport.


Journal ArticleDOI
TL;DR: Sodium sulfide inhibited N2O reduction markedly in cell suspensions and also in soil, an effect which may cause sulfidic habitats to act as sources of N2 O.
Abstract: The production and reduction of nitrous oxide (N2O) after the addition of N2O, nitrite (NO2−), or nitrate (NO3−) was studied in non-sterile soil, in sterilized soil inoculated with Pseudomonas aeruginosa, and in washed cell suspensions of this organism. Sodium sulfide (8 μmol S2− mL−1 or g−1) inhibited N2O reduction markedly in cell suspensions and also in soil, an effect which may cause sulfidic habitats to act as sources of N2O. Sodium thiosulfate (up to 64 μmol S2O32− g−1) showed no such effect. Acetylene (0.02 atm C2H2) completely inhibited the reduction of N2O by soil, but the combination of C2H2 with 8 μmol S2− g−1 permitted the complete reduction of 2 μmol added N2O g−1 within 3 days under the most favourable conditions. Under the same conditions, 8 μmol S2O32− g−1 permitted complete reduction of the N2O within 6 days. The rate of such reduction of N2O was decreased, but not inhibited completely, by raising the C2H2 concentration to 0.11 atm. The data have important implications for the effectivene...

Patent
19 Jan 1979
TL;DR: Olefine oxides are produced by contacting an olefine with oxygen in the presence of a silver containing catalyst and a chlorine-containing reaction modifier; the performance of the catalyst is improved by contacting it with a nitrate or nitrite forming substance for example nitric oxide as mentioned in this paper.
Abstract: Olefine oxides are produced by contacting an olefine with oxygen in the presence of a silver containing catalyst and a chlorine-containing reaction modifier; the performance of the catalyst is improved by contacting it with a nitrate or nitrite forming substance for example nitric oxide.

Journal ArticleDOI
08 Jun 1979-Science
TL;DR: The mechanism of cancer induction did not appear to be through the formation of nitrosamines but through a more direct effect of nitrite on the lymphocyte.
Abstract: Rats were exposed to sodium nitrite in food or water at concentrations of 0, 250, 1000, and 2000 parts per million. Lymphoma was increased in all groups fed nitrite; the overall combined incidence was 5.4 percent in 573 control rats and 10.2 percent in 1383 treated rats. The mechanism of cancer induction did not appear to be through the formation of nitrosamines but through a more direct effect of nitrite on the lymphocyte.

Journal ArticleDOI
TL;DR: The effect of Cd, Cu, Pb, and Zn on denitrification of three Pseudomonas species in a liquid culture medium (Giltay) and in autoclaved soil, as well as on the denitrifying activity of native soil, was investigated as mentioned in this paper.
Abstract: The effect of Cd, Cu, Pb, and Zn on denitrification of three Pseudomonas species in a liquid culture medium (Giltay) and in autoclaved soil, as well as on the denitrifying activity of native soil, was investigated. In Giltay medium, Cd in concentrations starting at 50 ..mu..g/ml strongly inhibited growth and denitrification of an unidentified Pseudomonas sp., P. aeruginosa, and P. denitrificans, while Zn and Pb did not influence the denitrifying activity even up to 500 ..mu..g/ml. Cu at 50 ..mu..g/ml inhibited denitrification of P. aeruginosa and the unidentified Pseudomonas sp.; however, it had no influence on P. denitrificans. When the three bacteria were inoculated into autoclaved soil their reaction to Cd and Cu was similar to that in Giltay medium, but the accumulation of nitrite was considerably higher. Zn, which showed no effect in the liquid medium at 500 ..mu..g/ml, inhibited the dentrifying activity of all bacteria in the soil at this concentration. Denitrification in native (nonautoclaved) soil was also inhibited by the addition of increasing amounts of heavy metals. This was indicated by an accumulation of nitrite and nitrous oxide which appeared to a lesser degree and for a shorter time period in nontreated samples.

Journal ArticleDOI
TL;DR: Investigation showed that samples of the oxidized protein at pH values 4, 5 and 6 bound NO to both haem c and d(1) components, but oxidized enzyme samples at pH7 and above formed their reduced ligand-bound forms when placed under an atmosphere of the gas.
Abstract: Determinations of iron content and dry-weight measurements on samples of Pseudomonas cytochrome oxidase were coupled with sodium dodecyl sulphate/polyacrylamide-gel-electrophoresis studies of both the native protein and covalently cross-linked oligomers in order to estimate the enzyme's molecular weight and spectral absorption coefficients. A value of eox.410=282×103 litre·mol−1·cm−1 was calculated for a dimeric protein molecule having a total molecular weight of 122000 (based on iron analysis). Steady-state kinetic observations of the enzyme-catalysed oxidation of reduced azurin by nitrite indicated a marked increase in enzyme inactivation as the pH was raised from 5.7 to 7.2. Since NO, a product of the nitrite reductase activity of Pseudomonas cytochrome oxidase, is known to bind to the enzyme, a study was undertaken to try to assess the potential of NO as a product inhibitor. Investigations showed that samples of the oxidized protein at pH values 4, 5 and 6 bound NO to both haem c and d1 components, but oxidized enzyme samples at pH7 and above formed their reduced ligand-bound forms when placed under an atmosphere of the gas. Ascorbate-reduced enzyme samples at pH4, 5, 6 and 7 were also found to bind NO at both haem components, although at pH7 the rate of haem c binding was very slow. At pH8 and 9 only the ferrohaem d1 bound NO. Titration experiments on the reduced protein over the pH range 5–7, with nitrite as a precursor of NO, showed that the haem d1 had a much higher affinity than the haem c: experiments at pH5.2 and 5.9 with NO-equilibrated solutions revealed the same pattern of behaviour with the oxidized enzyme.

Journal ArticleDOI
TL;DR: This is the first report in which patients with diagnosed gastric pathology related to a precancerous state were shown to have high levels of a putative carcinogen precursor, compatible with the original hypothesis of intragastric nitrite formation by bacterial reduction of nitrate and concomitant synthesis of carcinogenic N-nitroso compounds.
Abstract: Samples of gastric contents from 2 groups of patients from a region of high risk for gastric cancer were analyzed for pH, nitrite, nitrate, thiocyanate, and chloride. In each group, the patients could be divided into 2 subgroups: those with a gastric pH of less than 5 and those with a gastric pH of greater than 5. Above pH 5, nitrite was correlated with nitrate. The pH greater than 5 subgroups had significantly higher (P less than 0.01) nitrite content (20- to 100-fold). Some high- and low-nitrite samples were also analyzed for macro and trace metal ions, but differences were not significant. This is the first report in which patients with diagnosed gastric pathology related to a precancerous state were shown to have high levels of a putative carcinogen precursor. The results were compatible with our original hypothesis of intragastric nitrite formation by bacterial reduction of nitrate and concomitant synthesis of carcinogenic N-nitroso compounds.

Journal ArticleDOI
TL;DR: Pseudomonas aeruginosa can synthesize two distinct proteins which reduce nitrate to nitrite: an assimilatory nitrate reductase and a dissimilatory nitrates reductionase, if conditions of growth are fully aerobic, and if the latter is not synthesized and does not function.
Abstract: Pseudomonas aeruginosa can reduce nitrate to nitrite and evenutally to nitrogen gas by the denitrification pathway, thereby providing the organism with a mode of respiration and ATP generation in the absence of oxygen. P. aeruginosa can also reduce nitrate to nitrite through an assimilatory pathway that provides the cell with reduced nitrogen for biosyntheses. In order to establish whether this organism synthesizes a single nitrate reductase protein that functions in both pathways, or produces one for each pathway, we isolated mutants blocked in the assimilation of nitrate. These mutants are unaffected in the reduction of nitrate be the denitrification pathway, although they produce low or undectable levels of assimilatory nitrate reductase. On the basis of transductional analysis, the mutations were found to be distributed among four genes designated nasA, nasB, nasC, and nasD. Shifting a nasA mutant from anaerobic to aerobic growth eliminated the culture's ability to reduce nitrate, i.e. the anaerobic nitrate reductase cannot function in the presence of oxygen. Thus P. aeruginosa can synthesize two distinct proteins which reduce nitrate to nitrite: an assimilatory nitrate reductase and a dissimilatory nitrate reductase. If conditions of growth are fully aerobic, the latter is not synthesized and does not function. The former, synthesized under the control of at least four genes, is repressed by readily available nitrogen sources.

Journal ArticleDOI
01 Jan 1979-Planta
TL;DR: Nitrate, n-propanol and several respiratory inhibitors or uncouplers partly reversed the inhibitory effect of oxygen on nitrate reduction in leaf discs in the dark and some concentrations of 2,4-dinitrophenol and ioxynil reversed inhibition without affecting respiratory rates.
Abstract: 15N-labelled nitrate was used to show that nitrate reduction by leaf discs in darkness was suppressed by oxygen, whereas nitrite present within the cell could be reduced under aerobic dark conditions. In other experiments, unlabelled nitrite, allowed to accumulate in the tissue during the dark anaerobic reduction of nitrate was shown by chemical analysis to be metabolised during a subsequent dark aerobic period. Leaves of intact plants resembled incubated leaf discs in accumulating nitrite under anaerobic conditions. Nitrate, n-propanol and several respiratory inhibitors or uncouplers partly reversed the inhibitory effect of oxygen on nitrate reduction in leaf discs in the dark. Of these nitrate and propanol acted synergistically. Reversal was usually associated with inhibition of respiration but some concentrations of 2,4-dinitrophenol (DNP) and ioxynil reversed inhibition without affecting respiratory rates. Respiratory inhibitors and uncouplers stimulated nitrate reduction in the anaerobic in vivo assay i.e. in conditions where the respiratory process is non-functional. Freezing and thawing leaf discs diminished but did not eliminate the sensitivity of nitrate reduction to oxygen inhibition.

Journal ArticleDOI
TL;DR: The detection of the unique enzyme-NO complex is the first definitive EPR evidence for the mandatory liganding of nitric oxide with pure nitrite reductase during nitrite reduction.

Journal ArticleDOI
TL;DR: It was concluded that an increase in membrane permeability, and a decrease in ATP synthesis, were contributory causes of this phenomenon, although neither could explain the experimental observations completely.
Abstract: When excised sterile barley roots, from plants which had been grown in the presence of nitrate, were placed under low oxygen tensions, nitrite was released into the external solution. The maximum leakage of nitrite occurred under completely anaerobic conditions. Nitrite was also released from barley roots under aerobic conditions when uncouplers of oxidative phosphorylation (DNP, CCCP1, pentachlorophenol) or certain simple organic acids were supplied. Inhibitors of the Krebs cycle, or of respiratory electron transport, were much less effective in causing the loss of nitrite, possibly because these compounds did not in general inhibit root respiration severely. Nitrite release, in response to any of the above treatments, was accompanied by an accumulation of nitrite within the tissue. It was concluded that an increase in membrane permeability, and a decrease in ATP synthesis, were contributory causes of this phenomenon, although neither could explain the experimental observations completely. There was however no evidence that the pentose phosphate pathway, which is regarded as the source of reducing power for nitrite reduction, was inhibited under conditions which favoured nitrite release.


Book ChapterDOI
01 Jan 1979
TL;DR: In this article, it was shown that this 6-electron reaction is catalyzed by a single enzyme, the ironprotein nitrite reductase, without liberation of free intermediates.
Abstract: For most plants in their natural environment, nitrate is the immediate source of nitrogen. This nitrate must be converted to ammonia before it is combined with carbon compounds to form the various nitrogenous components of the cell. Since the nitrogen of nitrate has a formal charge of +5, whereas the nitrogen of ammonia has a formal charge of −3, an 8-electron reduction is required to convert nitrate to ammonia. This occurs in two steps. First, nitrate is reduced to nitrite in a 2-electron reduction catalyzed by the enzyme nitrate reductase, a flavoprotein containing heme and molybdenum. After many early efforts to identify intermediates in the further reduction of nitrite to ammonia, a consensus has been reached that this 6-electron reaction is catalyzed by a single enzyme, the ironprotein nitrite reductase, without liberation of free intermediates (Hewitt, 1975; Losada, 1976a; Zumft, 1976).

Journal ArticleDOI
TL;DR: The ingestion by normal adults of a meal including vegetables rich in nitrate led to a rapid increase in the salivary nitrite concentration, which was followed by a fall towards the fasting nitrite levels, although the concentration in the saliva remained elevated for as long as 21 hr.

Journal ArticleDOI
TL;DR: In this article, the effects of sodium nitrite and sorbic acid on C. botulinum growth and toxin production and residual nitrite depletion were studied in a mechanically deboned chicken meat (MDCM) frankfurter-type product, during 27°C temperature abuse.
Abstract: C. botulinum growth and toxin production and residual nitrite depletion were studied in a mechanically deboned chicken meat (MDCM) frankfurter-type product, during 27°C temperature abuse. A series of three trials were conducted in order to determine the effects of sodium nitrite and sorbic acid on the above parameters. Low nitrite concentrations (20 and 40 μg/g), did not influence C botulinum growth and toxin production. The addition of sorbic acid (0.2%) to these nitrite levels resulted in a significant extention of the time necessary for toxin to develop. The 0.1% sorbic acid level was ineffective. Nitrite concentrations of 156 μg/g doubled the time necessary, for botulinal toxin production, as did 0.2% sorbic acid alone. The magnitude of toxin production delay was increased five fold when 156 μg/g nitrite and 0.2% sorbic acid were combined. Nitrite depletion, was rapid during processing and 27°C incubation. Low residual nitrite concentrations were present for a longer time in nitrite-sorbic acid combination treatments, indicating that the presence of sorbic acid may delay depletion of residual nitrite. Gas production and spoilage of the product followed the same rate of development as toxin.

Journal ArticleDOI
TL;DR: In this paper, it was shown that the initial rate of reaction obeys the equation d[HNO2]/dt=V0=K[H NO2][NH 3OH+] 0.85 at very low initial hydroxylamine concentrations, but decreases towards zero at higher values of [NH 3 OH+]0.
Abstract: Hydroxylamine is oxidised by nitric acid to form dinitrogen monoxide and nitrous acid, the proportions varying with reaction conditions. The yield [HNO2]∞/[NH3OH+]0 is a maximum at ca. 4–5 mol dm–3 HNO3, and is also a function of the hydroxylamine concentration. In 5 mol dm–3 HNO3 the limiting yield is ca. 0.85 at very low initial hydroxylamine concentrations, but decreases towards zero at higher values of [NH3OH+]0. Reaction is only observed at sufficiently high nitric acid concentrations; at 25°C the cut-off point is ca. 2.5 mol dm–3 HNO3. The reaction is characterised by an induction period, followed by a rapid autocatalytic process. Addition of nitrite eliminates the induction period, while addition of nitrite scavengers completely prevents any reaction. Nitrous acid is an essential catalyst for the reaction, and the initial rate of reaction obeys the equation d[HNO2]/dt=V0=K[HNO2][NH3OH+]. Isotopic experiments, using 15N-enriched hydroxylamine show that virtually all of the N2O arises from reaction between HNO2 and hydroxylamine. The mechanism suggested involves oxidation of unprotonated hydroxylamine by N2O4 to form the nitroxyl diradical HNO; this is then further oxidised to HNO2, which reacts with hydroxylamine to form N2O.

Journal ArticleDOI
TL;DR: The effect of different types of water stress on nitrate and nitrite reductases of wheat leaves was investigated and the inhibition of nitrate reductase under water stress was attributed to both a direct inhibition and a reduced rate in enzyme synthesis.
Abstract: The effect of different types of water stress on nitrate and nitrite reductases of wheat (Triticum vulgare L. cv. Mivhor) leaves was investigated. Water stress was applied either to leaf tissue by its incubation in mannitol or various salt solutions, or to intact plants by exposure of the root system to low temperatures or to salinity. Nitrite reductase was much less sensitive to water stress than nitrate reductase, and was not sensitive to salinity up to osmotic potentials of about — 13 bars. The decrease in nitrite reductase activity by water stress was attributed to a direct inhibition of the enzyme rather than to a repression of enzyme synthesis. This was based on the fast response of the enzyme after exposure of leaf tissue to reduced osmotic potential, on the lack of a continuous decrease in enzyme activity during a prolonged stress, and on the fact that light activation of reductase was unaffected by water stress. The inhibition of nitrate reductase under water stress was attributed to both a direct inhibition and a reduced rate in enzyme synthesis. This is concluded from the fact that a decrease in its activity was obtained already within 1 h after stress application and from the fact that light induction of the enzyme was inhibited by stress.