Showing papers on "Nitrite published in 1971"
TL;DR: The measurement of nitrate reductase activity in intact plant tissue based on reduction of nitrates to nitrite is facilitated by the use of propanol and other organic solvents added to the incubation medium.
1,135 citations
TL;DR: This chapter discusses the determination of nitrate reductase from higher plants, and the stoichiometric relationship between nitrite produced and pyridine nucleotide or flavin oxidized is established.
Abstract: Publisher Summary This chapter discusses the determination of nitrate reductase from higher plants. Nitrate reductase is capable of utilizing reduced pyridinenucleotides, flavin, or benzyl viologen as electron donors for the reduction of nitrate to nitrite. These reductants can be added in the reduced form or generated enzymatically in the reaction mixture. Because the NADH-dependent nitrate reductase is most prevalent in plants, NADH has been the most commonly employed reductant. Enzyme activity is usually measured by the colorimetric determination of the nitrite formed during a timed incubation period at a fixed temperature, regardless of electron donor used. The activity can also be measured by following the oxidation of the pyridine nucleotides at 340 nm. The relative merits and limitations of these methods are discussed in the chapter. The stoichiometric relationship between nitrite produced and pyridine nucleotide or flavin oxidized is also established. In all purification methods so far developed, chromatography on calcium phosphate gel features prominently, used either in batches or in columns. Nitrate reductase precipitates with exceptional ease on addition of ammonium sulfate, and this step may be worth using more than once in a purification method.
259 citations
TL;DR: Pseudomonas perfectomarinus was found to grow anaerobically at the expense of nitrate, nitrite, or nitrous oxide but not chlorate or nitric oxide, and synthesized the denitrifying enzymes within 3 hr in the absence of oxygen or another acceptable inorganic oxidant.
Abstract: Pseudomonas perfectomarinus was found to grow anaerobically at the expense of nitrate, nitrite, or nitrous oxide but not chlorate or nitric oxide. In several repetitive experiments, anaerobic incubation in culture media containing nitrate revealed that an average of 82% of the cells in aerobically grown populations were converted to the capacity for respiration of nitrate. Although they did not form colonies under these conditions, the bacteria synthesized the denitrifying enzymes within 3 hr in the absence of oxygen or another acceptable inorganic oxidant. This was demonstrated by the ability, after anaerobic incubation, of cells and of extracts to reduce nitrite, nitric oxide, and nitrous oxide to nitrogen. From crude extracts of cells grown on nitrate, nitrite, or nitrous oxide, separate complex fractions were obtained that utilized reduced nicotinamide adenine dinucleotide as the source of electrons for the reduction of (i) nitrite to nitric oxide, (ii) nitric oxide to nitrous oxide, and (iii) nitrous oxide to nitrogen. Gas chromatographic analyses revealed that each of these fractions reduced only one of the nitrogenous oxides.
98 citations
94 citations
TL;DR: In the euphotic zone of the central North Pacific as discussed by the authors, the nitrite level changed unidirectionally for 10-24 hours and followed the kinetics of a first order reaction.
Abstract: Capacities for oxidation and reduction of inorganic nitrogen in the euphotic zone of the central North Pacific were estimated from the measurement of change with time of nitrite content in seawater samples. Regardless of whether ammonia, nitrate, or nitrite was the major component, if its concentration did not exceed 5–10 µg-atom N/liter, then the nitrite level changed unidirectionally for 10–24 hr and followed the kinetics of a first order reaction. In surface layers shallower than 30 m, capacities for both nitrite production from nitrate and consumption of nitrite were appreciable and they were enhanced several times by illumination. Phytoplankton seems mainly responsible for these processes. Insitu capacity for nitrite consumption was higher than that for nitrite production. But ammonia oxidation prevailed in the nitrite maximum layers located at about 70-m depth; the production rate of nitrite was of the order of 10‒4 µg-atom N liter‒1 hr‒1.
93 citations
TL;DR: In this paper, the autoxidation of hydroxylamine in aqueous alkali is shown to proceed by attack of oxygen on a deprotonated species yielding nitroxyl ion which can be oxidised further to peroxonitrite.
Abstract: The autoxidation of hydroxylamine in aqueous alkali is shown to proceed by attack of oxygen on a deprotonated species yielding nitroxyl ion which can be oxidised further to peroxonitrite. In the presence of a metal sequestering agent (edta) the peroxonitrite ion is stabilised, although isomerising slowly to nitrate. A little nitrite is also formed. Decrease in pH leads to increasing production of gaseous products. In the presence of catalytic metal ions, nitrite is the main product, the hydroxylamine being largely consumed via reaction with peroxonitrite. Increasing concentration of copper(II) ions resulted in increasing production of nitrous oxide. A mechanism is presented for oxygen attack on hydroxylamine and a number of other autoxidation studies on N- and O-substituted hydroxylamines discussed.
86 citations
TL;DR: Experiments with N-methylaniline and morpholine have shown that thiocyanate, a normal constituent of human saliva, has a pronounced catalytic effect on the reaction between nitrite and secondary amines to form nitrosamines.
80 citations
TL;DR: In this article, a method for the extraction of nitrate and nitrite from meat by heating at 80 °C for 10 minutes to coagulate the protein and inactivate nitrates and nitrites reductase activity and subsequently treating with alumina cream.
Abstract: A method has been developed for the extraction of nitrate and nitrite from meat by heating at 80 °C for 10 minutes to coagulate the protein and inactivate nitrate and nitrite reductase activity and subsequently treating with alumina cream. The latter treatment alone was used for the clarification of curing brines.A method for the reduction of nitrate to nitrite by shaking with cadmium has been developed that is quicker, as it takes 5 minutes, than column reduction, which requires 40 to 60 minutes. Quantitative recoveries of nitrate as nitrite were obtained.Methods of determining nitrate as nitrite involving the use of the diazo compounds formed between sulphanilic acid and each of the four coupling agents 1-naphthylamine, N-1-naphthylethylenediamine, 1-naphthylamine-7-sulphonic acid and 1-naphthol were investigated. N-1-Naphthylethylene-diamine is recommended because of the short time (10 minutes) required for maximum colour development.
80 citations
TL;DR: This chapter describes the purification procedure for the enzyme from spinach leaves, and indicates that among the artificial substitutes for ferredoxin, methyl viologen is the most effective one examined.
Abstract: Publisher Summary This chapter discusses the determination of nitrite reductase. The usual assay involves sodium dithionite as reductant and either ferredoxin or its artificial substitute, methyl viologen, as the electron carrier. Enzymatic activity can be best followed by measuring colorimetrically the rate of disappearance of nitrite. One unit of enzyme is the amount that catalyzes the reduction of 1 μmole of nitrite per minute. Specific activity is expressed as units per milligram of protein. The protein content of the enzyme preparation is determined by the ultraviolet absorption procedure of Warburg and Christian. This chapter describes the purification procedure for the enzyme from spinach leaves. The purified enzyme can be stored in deep-freeze for a month with no loss in activity. By heating at 60 ° C for 10 minutes, the activity is totally lost. There is a marked specificity for reduced ferredoxin as the natural electron donor. The purified enzyme is completely inactive with either reduced pyridine nucleotides or reduced flavin nucleotides as electron donor. Among the artificial substitutes for ferredoxin, methyl viologen is the most effective one examined.
76 citations
TL;DR: Both nitrate-induced and noninduced aleurone layers were able to reduce nitrite anaerobically when the concentration of substrate in the assay medium was reduced from 250 mum to 25 mum, and nitrite uptake was relatively insensitive to anaerOBiosis and to the inhibitors tested.
Abstract: A method has been devised for the detection and measurement of nitrite reductase activity in intact barley (Hordeum vulgare L. cv. Himalaya) aleurone layers. The technique involves feeding aleurone layers nitrite and measuring nitrite disappearance after a given time period. The method also allows simultaneous determination of nitrite uptake by the tissue. Quantitative recovery of nitrite is obtained by rapid heating of tissue in the presence of dimethyl sulfoxide.Using the procedure described, nitrite reductase activity in intact barley aleurone layers was determined. Enzyme activity was increased by prior incubation of the tissue with nitrate, but considerable activity was present in tissue incubated without nitrate. Nitrate-induced activity was inhibited by cycloheximide but not by actinomycin D. Enzyme activity in induced layers was inhibited by 2,4-dinitrophenol, and partially by antimycin A and 2-n-heptyl-4-hydroxyquinoline N-oxide. Activity in noninduced tissue appeared to be less sensitive to these respiratory inhibitors. In contrast, both activities were inhibited more than 90% by anaerobiosis; but nitrate-induced and noninduced aleurone layers were able to reduce nitrite anaerobically when the concentration of substrate in the assay medium was reduced from 250 mum to 25 mum. Nitrite uptake was relatively insensitive to anaerobiosis and to the inhibitors tested.Nitrite depletion from the medium by aleurone layers was rapid at pH 4.5 and negligible at pH 7.5. Nitrite accumulated at pH 4.5 under anaerobic conditions was rapidly released when the tissue was transferred to medium at pH 7.5. Nitrite release at pH 7.5 occurred whether the tissue was maintained under anaerobic or aerobic conditions.
76 citations
TL;DR: In this article, two new and even more sensitive pairs of reagents for nitrate analysis were introduced that do not involve the use of a possibly carcinogenic naphthylamine.
TL;DR: A nitrate reductase (NADH:nitrate oxidoreductase, EC 1.6.1), which catalyzes the reduction of nitrate to nitrite by NADH, has been found to be present in fresh extracts of Nitrate-grown Chlorella pyrenoidosa in the form of a precursor of low activity.
TL;DR: It is taken as evidence that nitrate does not have to be reduced to nitrite to cause an increase in nitrite reductase activity, and that nitrite reduces nitrate more rapidly than nitrate and is more stable and its decay kinetics are more complex in vivo, compared to nitrate reduct enzyme.
TL;DR: The synthesis of nitrosopiperidine in rats from nitrite and piperidine is reported, both in the stomach and in the small intestine in vivo, and in vitro at near neutral pH values in the presence of enteric bacteria.
Abstract: SINCE the first report of hepatic cancer in rats induced by nitrosodimethylamine1, many nitrosamines have been shown to be carcinogenic in a wide range of organs of a wide variety of species1–4. Following the suggestion that dietary nitrite and secondary amines might interact in the human stomach to form nitrosamines5, such synthesis has been demonstrated in vitro with animal and human gastric juice6,7, and in vivo in laboratory animals7 and man8; nitrosamine synthesis was pH-dependent7–10. Nitrosamines can also be synthesized in vitro at near neutral pH values in the presence of enteric bacteria11; yields of nitrosamines are also determined by the basicity of the secondary amine. Presumptive evidence for in vivo synthesis of nitrosamines has been demonstrated by the induction of tumours in rats following chronic feeding of nitrite and secondary amines11. We report here the synthesis of nitrosopiperidine in rats from nitrite and piperidine in gastric contents in vitro, and in the stomach and in the small intestine in vivo.
TL;DR: Creatine reacts with nitrite under acid conditions to produce first sarcosine and then N-nitrososarcosine, which is a weak carcinogen in the rat, and either creatinine-5-oxime or 1-methylhydantoin-5,oxime, depending on reaction conditions.
Abstract: Creatine reacts with nitrite under acid conditions to produce first sarcosine and then N-nitrososarcosine, which is a weak carcinogen in the rat. Creatinine reacts with acidified nitrite to produce either creatinine-5-oxime or 1-methylhydantoin-5-oxime, depending on reaction conditions. The toxicity and environmental significance of these compounds is not yet known.
TL;DR: Quantitative EPR measurements indicate that all the c -type cytochromes involved in nitrite reduction are in the heme-NO complex forms and that these complexes account for about 15% of the total nitric oxide observed.
TL;DR: In this paper, it was shown that formation of volatile nitrosamines occurs when nitrite and alkylamines are present in the same media, and the toxicity of these was demonstrated with mink as test animals.
Abstract: Experiments have shown that Formation of volatile nitrosamines occurs when nitrite and alkylamines are present in the same media. Heterocyclic amines such as pyrrolidine and piperidine contribute to nitrosamine Formation as well. Precursor substances leading to nitrosamine Formation are, besides various biogenic amines, certain amino acids and proteins from meat and Fish if nitrite is present in sufficient quantities and high temperature treatment is used. In order to prevent the Formed nitrosamines From escaping at high temperatures a protecting colloid must be present. The amount and type of nitrosamine Formed under various experimental conditions have been studied by quantitative and qualitative methods. In cases where large amounts of nitrosamines were Formed, the toxicity of these was demonstrated with mink as test animals.
TL;DR: Pseudomonas sp.
Abstract: Pseudomonas sp. was isolated from sewage effluent by elective culture with nitrilotriacetic acid (NTA) as its sole nitrogen and carbon source for growth. NTA-nitrogen was converted to biomass and ammonium by growing cultures with small quantities of nitrite (< 1 ppm) being produced. Washed cell suspensions degraded all of the NTA-nitrogen to ammonium before total conversion of the NTA-carbon to carbon dioxide and water. Resting cell suspensions grown from NTA oxidized NTA, aminodiacetic acid, and glycine immediately, whereas methylaminodiacetic acid was oxidized only after an adaptive lag period, and sarcosine was not oxidized at all. Oxidation of aminodiacetic acid was always more rapid than NTA. Nitrosamines or other nitroso compounds were not found in culture or resting cell supernatants incubated with NTA.
TL;DR: Hyperbaric oxygen decreases nitrite-induced mortality and methemoglobinemia and had no effect on the erythrocyte reductase systems in reducing methemoglobin.
Abstract: SummaryHyperbaric oxygen decreases nitrite-induced mortality and methemoglobinemia. The action of HPO in reducing methemoglobin levels is brought about by hindering the oxidation of hemoglobin by nitrite. HPO had no effect on the erythrocyte reductase systems in reducing methemoglobin.
TL;DR: In this paper, the reactions of peroxonitrite with the nucleophiles CN, I, and SCN have been studied in alkali, and the results are used for a comparison of peroxide-containing compounds with other peroxides.
Abstract: The reactions of peroxonitrite with the nucleophiles CN–, I–, and SCN– have been studied in alkali. Oxygen-atom transfer occurs from peroxonitrite to the nucleophile, with the production of nitrite. The reaction with cyanide is independent of pH, but that with iodide is subject to acid catalysis, indicating that peroxonitrous acid is the reacting species. These results are used for a comparison of peroxonitrite with other peroxides. The metal-ion catalysed self decomposition of peroxonitrite and the metal-ion catalysed reaction with peroxide also led to the production of nitrite. Mechanisms are suggested for these reactions.
TL;DR: The applicability of the method to the differential determination of N -methylhydroxylamine and free hydroxylamine has been demonstrated and the oxidation was found to be critically pH-dependent but the yield of nitrite could not be made quantitative.
TL;DR: Chloroplasts ruptured by osmotic shock fail to reduce nitrite in the absence of additional components, indicating a probable reduction of nitrite to ammonia.
Abstract: Nitrate reductase was not found to be present in or associated with partially purified, intact chloroplasts aqueously isolated from Wolffia arrhiza. Such chloroplasts are capable of using nitrite but not nitrate as an electron acceptor during light-stimulated electron transport in the absence of additional cytoplasmic components. When nitrite acts as an electron acceptor under these conditions, on the average 1.5 moles of oxygen are evolved per mole of nitrite reduced by the chloroplasts, indicating a probable reduction of nitrite to ammonia. Chloroplasts ruptured by osmotic shock fail to reduce nitrite in the absence of additional components.
TL;DR: In this paper, a sensitive and accurate method for the determination of 0.001-0.100 μg-at. NO 2 - -N per liter in sea water is described, where the sample (500-1000 ml) is treated with sulfanilic acid and N-(1-naphthyl)ethylenediamine, and drawn through a column of Dowex 1-X8 resin.
TL;DR: The distribution of nitrite and nitrate in the tropical Pacific Ocean along the 155°W meridian was investigated during the KH-69-4 cruise of the R. V. Hakuho Maru (Aug. 12-Nov. 13, 1969) as mentioned in this paper.
TL;DR: In this article, a sensitive fluorimetric method has been developed for the determination of nitrate based on the reduction of Nitrate to nitrite with hydrazine sulfate and the subsequent determination of the nitrite formed with 2, 3-diaminonaphthalene.
Abstract: A sensitive fluorimetric method has been developed for the determination of nitrate based on the reduction of nitrate to nitrite with hydrazine sulfate and the subsequent determination of the nitrite formed with 2, 3-diaminonaphthalene. Solvent effect on fluorescence intensity, optimum reaction conditions, and sensitivity of the method are discussed.
TL;DR: The localization of the nitrate-assimilating enzymes, nitrate reductase, nitrite reduct enzyme, and glutamate dehydrogenase in Zea mays, Gomphrena globosa, and Sorghum sudanense was studied by differential grinding and nitrate reduction to nitrite appears to occur primarily in mesophyll cells.
Abstract: The vascular bundle of leaves with the C4-pathway of photosynthesis is usually surrounded by two concentric chlorophyllous cell layers: an outer mesophyll layer and an inner bundle sheath layer. The localization of the nitrate-assimilating enzymes, nitrate reductase, nitrite reductase, and glutamate dehydrogenase in Zea mays, Gomphrena globosa, and Sorghum sudanense was studied by differential grinding. Nitrate reduction to nitrite appears to occur primarily in mesophyll cells. The nitrate content of the mesophyll cells was much higher than the nitrate content of the bundle sheath cells. The distribution of nitrite reductase seemed to be related to the presence of chloroplasts with grana. Ammonia incorporation into organic compounds by glutamate dehydrogenase was localized in the bundle sheath cells.
TL;DR: The most important types of micro-organisms isolated from the bacons were Micrococcus, yeasts, Vibrio, Acinetobacter, Alcaligenes and Arthrobacter-Corynebacterium, which appeared to be associated with phase 2 changes.
Abstract: Total microbial growth and chemical changes in aerobically stored bacon lean were found to fall into 2 phases. Phase 1: there was an increase in total microbial load to c. 109/g, during which most of the nitrate was broken down and there was an accumulation of nitrite. Phase 2: the microbial load increased further to c. 1010/g and during this time most of the accumulated nitrite was broken down to unknown products, so that at the end of the experiments most of the nitrate and nitrite had disappeared from the bacon.
The most important types of micro-organisms isolated from the bacons were Micrococcus, yeasts, Vibrio, Acinetobacter, Alcaligenes and Arthrobacter-Corynebacterium. The latter 3 types appeared to be associated with phase 2 changes.