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Granger J, Boshers DS, Böhlke JK, Yu D, Chen N, Tobias CR. The influence of sample matrix on the accuracy of nitrite N and O isotope ratio analyses with the azide method. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34:e8569. [PMID: 31472482 DOI: 10.1002/rcm.8569] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/23/2019] [Accepted: 08/24/2019] [Indexed: 06/10/2023]
Abstract
RATIONALE The isotope ratios of nitrogen (15 N/14 N) and oxygen (18 O/16 O) in nitrite (NO2 - ) can be measured by conversion of the nitrite into nitrous oxide (N2 O) with azide, followed by mass spectrometric analysis of N2 O by gas chromatography isotope ratio mass spectrometry (GC/IRMS). While applying this method to brackish samples, we noticed that the N and O isotope ratio measurements of NO2 - are highly sensitive to sample salinity and to the pH at which samples are preserved. METHODS We investigated the influence of sample salinity and sample preservation pH on the N and O isotope ratios of the N2 O produced from the reaction of NO2 - with azide. The N2 O isotope ratios were measured by GC/IRMS. RESULTS Under the experimental reaction conditions, the conversion of NO2 - into N2 O was less complete in lower salinity solutions, resulting in respective N and O isotopic offsets of +2.5‰ and -14.0‰ compared with seawater solutions. Differences in salinity were also associated with differences in the fraction of O atoms exchanged between NO2 - and water during the reaction. Similarly, aqueous NO2 - samples preserved at elevated pH values resulted in the incomplete conversion of NO2 - into N2 O by azide, and consequent pH-dependent isotopic offsets, as well as differences in the fraction of O atoms exchanged with water. The addition of sodium chloride to the reaction matrix of samples and standards largely mitigated salinity-dependent isotopic offsets in the N2 O product, and nearly homogenized the fraction of O atom exchange among samples of different salinity. A test of the hypobromite-azide method to measure N isotope ratios of ammonium by conversion into NO2 - then N2 O revealed no influence of sample salinity on the N isotope ratios of the N2 O product. CONCLUSIONS We outline recommendations to mitigate potential matrix effects among samples and standards, to improve the accuracy of N and O isotope ratios in NO2 - measured with the azide method.
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Affiliation(s)
- Julie Granger
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | - Danielle S Boshers
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
| | | | - Dan Yu
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Nengwang Chen
- Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen, China
| | - Craig R Tobias
- Department of Marine Sciences, University of Connecticut, Groton, CT, USA
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Rex D, Clough TJ, Richards KG, Condron LM, de Klein CAM, Morales SE, Lanigan GJ. Impact of nitrogen compounds on fungal and bacterial contributions to codenitrification in a pasture soil. Sci Rep 2019; 9:13371. [PMID: 31527802 PMCID: PMC6746759 DOI: 10.1038/s41598-019-49989-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 08/15/2019] [Indexed: 11/09/2022] Open
Abstract
Ruminant urine patches on grazed grassland are a significant source of agricultural nitrous oxide (N2O) emissions. Of the many biotic and abiotic N2O production mechanisms initiated following urine-urea deposition, codenitrification resulting in the formation of hybrid N2O, is one of the least understood. Codenitrification forms hybrid N2O via biotic N-nitrosation, co-metabolising organic and inorganic N compounds (N substrates) to produce N2O. The objective of this study was to assess the relative significance of different N substrates on codenitrification and to determine the contributions of fungi and bacteria to codenitrification. 15N-labelled ammonium, hydroxylamine (NH2OH) and two amino acids (phenylalanine or glycine) were applied, separately, to sieved soil mesocosms eight days after a simulated urine event, in the absence or presence of bacterial and fungal inhibitors. Soil chemical variables and N2O fluxes were monitored and the codenitrified N2O fluxes determined. Fungal inhibition decreased N2O fluxes by ca. 40% for both amino acid treatments, while bacterial inhibition only decreased the N2O flux of the glycine treatment, by 14%. Hydroxylamine (NH2OH) generated the highest N2O fluxes which declined with either fungal or bacterial inhibition alone, while combined inhibition resulted in a 60% decrease in the N2O flux. All the N substrates examined participated to some extent in codenitrification. Trends for codenitrification under the NH2OH substrate treatment followed those of total N2O fluxes (85.7% of total N2O flux). Codenitrification fluxes under non-NH2OH substrate treatments (0.7-1.2% of total N2O flux) were two orders of magnitude lower, and significant decreases in these treatments only occurred with fungal inhibition in the amino acid substrate treatments. These results demonstrate that in situ studies are required to better understand the dynamics of codenitrification substrates in grazed pasture soils and the associated role that fungi have with respect to codenitrification.
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Affiliation(s)
- David Rex
- Department of Soil and Physical Sciences, Lincoln University, Lincoln, New Zealand. .,Teagasc, Environmental Research Centre, Johnstown Castle, Wexford, Ireland.
| | - Timothy J Clough
- Department of Soil and Physical Sciences, Lincoln University, Lincoln, New Zealand
| | - Karl G Richards
- Teagasc, Environmental Research Centre, Johnstown Castle, Wexford, Ireland
| | - Leo M Condron
- Department of Soil and Physical Sciences, Lincoln University, Lincoln, New Zealand
| | | | - Sergio E Morales
- Department of Microbiology and Immunology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Gary J Lanigan
- Teagasc, Environmental Research Centre, Johnstown Castle, Wexford, Ireland
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Shakoor A, Abdullah M, Yousaf B, Amina, Ma Y. Atmospheric emission of nitric oxide and processes involved in its biogeochemical transformation in terrestrial environment. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2016:10.1007/s11356-016-7823-6. [PMID: 27771880 DOI: 10.1007/s11356-016-7823-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Accepted: 10/03/2016] [Indexed: 06/06/2023]
Abstract
Nitric oxide (NO) is an intra- and intercellular gaseous signaling molecule with a broad spectrum of regulatory functions in biological system. Its emissions are produced by both natural and anthropogenic sources; however, soils are among the most important sources of NO. Nitric oxide plays a decisive role in environmental-atmospheric chemistry by controlling the tropospheric photochemical production of ozone and regulates formation of various oxidizing agents such as hydroxyl radical (OH), which contributes to the formation of acid of precipitates. Consequently, for developing strategies to overcome the deleterious impact of NO on terrestrial ecosystem, it is mandatory to have reliable information about the exact emission mechanism and processes involved in its transformation in soil-atmospheric system. Although the formation process of NO is a complex phenomenon and depends on many physicochemical characteristics, such as organic matter, soil pH, soil moisture, soil temperature, etc., this review provides comprehensive updates about the emission characteristics and biogeochemical transformation mechanism of NO. Moreover, this article will also be helpful to understand the processes involved in the consumption of NO in soils. Further studies describing the functions of NO in biological system are also discussed.
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Affiliation(s)
- Awais Shakoor
- School of Resources and Environment, Anhui Agricultural University, Hefei, 230036, China
| | - Muhammad Abdullah
- State-Key Laboratory of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei, 230036, China
| | - Balal Yousaf
- CAS-Key Laboratory of Crust-Mantle Materials and the Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, 230026, China
| | - Amina
- School of Resources and Environment, Anhui Agricultural University, Hefei, 230036, China
| | - Youhua Ma
- School of Resources and Environment, Anhui Agricultural University, Hefei, 230036, China.
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Selbie DR, Lanigan GJ, Laughlin RJ, Di HJ, Moir JL, Cameron KC, Clough TJ, Watson CJ, Grant J, Somers C, Richards KG. Confirmation of co-denitrification in grazed grassland. Sci Rep 2015; 5:17361. [PMID: 26615911 PMCID: PMC4663629 DOI: 10.1038/srep17361] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Accepted: 10/20/2015] [Indexed: 11/21/2022] Open
Abstract
Pasture-based livestock systems are often associated with losses of reactive forms of nitrogen (N) to the environment. Research has focused on losses to air and water due to the health, economic and environmental impacts of reactive N. Di-nitrogen (N2) emissions are still poorly characterized, both in terms of the processes involved and their magnitude, due to financial and methodological constraints. Relatively few studies have focused on quantifying N2 losses in vivo and fewer still have examined the relative contribution of the different N2 emission processes, particularly in grazed pastures. We used a combination of a high 15N isotopic enrichment of applied N with a high precision of determination of 15N isotopic enrichment by isotope-ratio mass spectrometry to measure N2 emissions in the field. We report that 55.8 g N m−2 (95%, CI 38 to 77 g m−2) was emitted as N2 by the process of co-denitrification in pastoral soils over 123 days following urine deposition (100 g N m−2), compared to only 1.1 g N m−2 (0.4 to 2.8 g m−2) from denitrification. This study provides strong evidence for co-denitrification as a major N2 production pathway, which has significant implications for understanding the N budgets of pastoral ecosystems.
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Affiliation(s)
- Diana R Selbie
- Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland.,AgResearch, Ruakura Research Centre, Hamilton, New Zealand.,Soil &Physical Sciences Department, Lincoln University, Christchurch, New Zealand
| | - Gary J Lanigan
- Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland
| | - Ronald J Laughlin
- Agri-Environment Branch, Agri-Food &Biosciences Institute, Belfast BT9 5PX, UK
| | - Hong J Di
- Soil &Physical Sciences Department, Lincoln University, Christchurch, New Zealand
| | - James L Moir
- Soil &Physical Sciences Department, Lincoln University, Christchurch, New Zealand
| | - Keith C Cameron
- Soil &Physical Sciences Department, Lincoln University, Christchurch, New Zealand
| | - Tim J Clough
- Soil &Physical Sciences Department, Lincoln University, Christchurch, New Zealand
| | - Catherine J Watson
- Agri-Environment Branch, Agri-Food &Biosciences Institute, Belfast BT9 5PX, UK
| | - James Grant
- Statistics and Applied Physics, Teagasc, Ashtown, Dublin 15, Ireland
| | - Cathal Somers
- Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland
| | - Karl G Richards
- Teagasc, Johnstown Castle, Environmental Research Centre, County Wexford, Ireland
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Zou Y, Hirono Y, Yanai Y, Hattori S, Toyoda S, Yoshida N. Rainwater, soil water, and soil nitrate effects on oxygen isotope ratios of nitrous oxide produced in a green tea (Camellia sinensis) field in Japan. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:891-900. [PMID: 26377018 DOI: 10.1002/rcm.7176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 02/14/2015] [Accepted: 02/20/2015] [Indexed: 06/05/2023]
Abstract
RATIONALE The oxygen exchange fraction between soil H(2)O and N(2)O precursors differs in soils depending on the responsible N(2)O-producing process: nitrification or denitrification. This study investigated the O-exchange between soil H(2)O and N(2)O precursors in a green tea field with high N(2)O emissions. METHODS The rainwater δ(18)O value was measured using cavity ring-down spectrometry (CRDS) and compared with that of soil water collected under the tea plant canopy and between tea plant rows. The intramolecular (15)N site preference in (β) N(α) NO (SP = δ(15)N(α) - δ(15)N(β)) was determined after measuring the δ(15)N(α) and δ(15)N(bulk) values using gas chromatography/isotope ratio mass spectrometry (GC/IRMS), and the δ(18) O values of N(2)O and NO(3)(-) were also measured using GC/IRMS. RESULTS The range of δ(18)O values of rainwater (-11.15‰ to -4.91‰) was wider than that of soil water (-7.94‰ to -5.64‰). The δ(18)O value of soil water at 50 cm depth was not immediately affected by rainwater. At 10 cm and 20 cm depths of soil between tea plant rows, linear regression analyses of δ(18)O-N(2)O (relative to δ(18)O-NO(3)(-)) versus δ(18) O-H(2)O (relative to δ(18)O-NO(3)(-)) yielded slopes of 0.76-0.80 and intercepts of 31-35‰. CONCLUSIONS In soil between tea plant rows, the fraction of O-exchange between H(2)O and N(2)O precursors was approximately 80%. Assuming that denitrification dominated N(2)O production, the net (18)O-isotope effect for denitrification (NO(3)(-) reduction to N(2)O) was approximately 31-35‰, reflecting the upland condition of the tea field.
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Affiliation(s)
- Yun Zou
- Dept. of Environmental Science and Technology, Tokyo Institute of Technology G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan
| | - Yuhei Hirono
- NARO Institute of Vegetable and Tea Science, 2769, Kanaya-Shishidoi, Shimada, Shizuoka, 428-8501, Japan
| | - Yosuke Yanai
- NARO Institute of Vegetable and Tea Science, 3-1-1 Kannondai, Tsukuba, Ibaraki, 305-8666, Japan
| | - Shohei Hattori
- Dept. of Environmental Chemistry and Engineering, Tokyo Institute of Technology G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan
| | - Sakae Toyoda
- Dept. of Environmental Science and Technology, Tokyo Institute of Technology G1-26, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan
| | - Naohiro Yoshida
- Dept. of Environmental Chemistry and Engineering, Tokyo Institute of Technology G1-17, 4259 Nagatsuta, Midori-ku, Yokohama, 226-8502, Japan
- Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, 152-8551, Japan
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Rohe L, Anderson TH, Braker G, Flessa H, Giesemann A, Lewicka-Szczebak D, Wrage-Mönnig N, Well R. Dual isotope and isotopomer signatures of nitrous oxide from fungal denitrification--a pure culture study. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:1893-1903. [PMID: 25088133 DOI: 10.1002/rcm.6975] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 06/27/2014] [Accepted: 06/27/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE The contribution of fungal denitrification to the emission of the greenhouse gas nitrous oxide (N2O) from soil has not yet been sufficiently investigated. The intramolecular (15)N site preference (SP) of N2O could provide a tool to distinguish between N2O produced by bacteria or fungi, since in previous studies fungi exhibited much higher SP values than bacteria. METHODS To further constrain isotopic evidence of fungal denitrification, we incubated six soil fungal strains under denitrifying conditions, with either NO3(-) or NO2(-) as the electron acceptor, and measured the isotopic signature (δ(18)O, δ(15)Nbulk and SP values) of the N2O produced. The nitrogen isotopic fractionation was calculated and the oxygen isotope exchange associated with particular fungal enzymes was estimated. RESULTS Five fungi of the order Hypocreales produced N2O with a SP of 35.1 ± 1.7 ‰ after 7 days of anaerobic incubation independent of the electron acceptor, whereas one Sordariales species produced N2O from NO2(-) only, with a SP value of 21.9 ± 1.4 ‰. Smaller isotope effects of (15)Nbulk were associated with larger N2O production. The δ(18)O values were influenced by oxygen exchange between water and denitrification intermediates, which occurred primarily at the nitrite reduction step. CONCLUSIONS Our results confirm that SP of N2O is a promising tool to differentiate between fungal and bacterial N2O from denitrification. Modelling of oxygen isotope fractionation processes indicated that the contribution of the NO2(-) and NO reduction steps to the total oxygen exchange differed among the various fungal species studied. However, more information is needed about different biological orders of fungi as they may differ in denitrification enzymes and consequently in the SP and δ(18)O values of the N2O produced.
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Affiliation(s)
- Lena Rohe
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 50, D-38116, Braunschweig, Germany; University of Göttingen, Department of Crop Sciences, Institute of Grassland Science, von-Siebold-Straße 8, D-37075, Göttingen, Germany
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7
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Rohe L, Anderson TH, Braker G, Flessa H, Giesemann A, Wrage-Mönnig N, Well R. Fungal oxygen exchange between denitrification intermediates and water. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:377-384. [PMID: 24395505 DOI: 10.1002/rcm.6790] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 11/14/2013] [Accepted: 11/20/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE Fungi can contribute greatly to N2O production from denitrification. Therefore, it is important to quantify the isotopic signature of fungal N2O. The isotopic composition of N2O can be used to identify and analyze the processes of N2O production and N2O reduction. In contrast to bacteria, information about the oxygen exchange between denitrification intermediates and water during fungal denitrification is lacking, impeding the explanatory power of stable isotope methods. METHODS Six fungal species were anaerobically incubated with the electron acceptors nitrate or nitrite and (18)O-labeled water to determine the oxygen exchange between denitrification intermediates and water. After seven days of incubation, gas samples were analyzed for N2O isotopologues by isotope ratio mass spectrometry. RESULTS All the fungal species produced N2O. N2O production was greater when nitrite was the sole electron acceptor (129 to 6558 nmol N2O g dw(-1) h(-1)) than when nitrate was the electron acceptor (6 to 47 nmol N2O g dw(-1) h(-1)). Oxygen exchange was complete with nitrate as electron acceptor in one of five fungi and with nitrite in two of six fungi. Oxygen exchange of the other fungi varied (41 to 89% with nitrite and 11 to 61% with nitrate). CONCLUSIONS This is the first report on oxygen exchange with water during fungal denitrification. The exchange appears to be within the range previously reported for bacterial denitrification. This adds to the difficulty of differentiating N2O producing processes based on the origin of N2O-O. However, the large oxygen exchange repeatedly observed for bacteria and now also fungi could lead to less variability in the δ(18)O values of N2O from soils, which could facilitate the assessment of the extent of N2O reduction.
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Affiliation(s)
- Lena Rohe
- Thünen Institute of Climate-Smart Agriculture, Bundesallee 50, D-38116, Braunschweig, Germany; University of Göttingen, Department of Crop Sciences, Institute of Grassland Science, von-Siebold-Str. 8, D-37075, Göttingen, Germany
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8
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Smith NA. CAMBRIDGE PRIZE LECTURE NITRATE REDUCTION AND N-NITROSATION IN BREWING*. JOURNAL OF THE INSTITUTE OF BREWING 2013. [DOI: 10.1002/j.2050-0416.1994.tb00835.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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9
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Smith NA, Smith P, Woodruff CA. THE ROLE OFBACILLUSspp. IN N-NITROSAMINE FORMATION DURING WORT PRODUCTION. JOURNAL OF THE INSTITUTE OF BREWING 2013. [DOI: 10.1002/j.2050-0416.1992.tb01124.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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10
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Baumgärtner M, Conrad R. Role of nitrate and nitrite for production and consumption of nitric oxide during denitrification in soil. FEMS Microbiol Ecol 2011. [DOI: 10.1111/j.1574-6941.1992.tb01649.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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Kool DM, Van Groenigen JW, Wrage N. Source Determination of Nitrous Oxide Based on Nitrogen and Oxygen Isotope Tracing. Methods Enzymol 2011; 496:139-60. [DOI: 10.1016/b978-0-12-386489-5.00006-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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12
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A simple and rapid GC/MS method for the simultaneous determination of gaseous metabolites. J Microbiol Methods 2010; 84:46-51. [PMID: 20971136 DOI: 10.1016/j.mimet.2010.10.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2010] [Revised: 10/13/2010] [Accepted: 10/13/2010] [Indexed: 11/20/2022]
Abstract
We modified and tuned a commercial model of a gas chromatography/mass spectrometry (GC/MS) instrument to develop a simple and rapid method for the simultaneous quantification of a variety of gas species. Using the developed method with the newly modified instrument, gas species such as H(2), N(2), O(2), CO, NO, CH(4), CO(2), and N(2)O, which are common components of microbial metabolism, were accurately identified based on their retention times and/or mass-to-charge ratios (m/z) in less than 2.5 min. By examining the sensitivities and dynamic ranges for the detection of H(2), N(2), O(2), CH(4), CO(2), and N(2)O, it was demonstrated that the method developed in this study was sufficient for accurately monitoring the production and the consumption of these gaseous species during microbial metabolism. The utility of the new method was demonstrated by a denitrification study with Pseudomonas aureofaciens ATCC 13985(T). This method will be suitable for a variety of applications requiring the identification of gaseous metabolites in microorganisms, microbial communities, and natural ecosystems.
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Kool DM, Wrage N, Oenema O, Harris D, Van Groenigen JW. The 18O signature of biogenic nitrous oxide is determined by O exchange with water. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2009; 23:104-108. [PMID: 19061209 DOI: 10.1002/rcm.3859] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
To effectively mitigate emissions of the greenhouse gas nitrous oxide (N(2)O) it is essential to understand the biochemical pathways by which it is produced. The (18)O signature of N(2)O is increasingly used to characterize these processes. However, assumptions on the origin of the O atom and resultant isotopic composition of N(2)O that are based on reaction stoichiometry may be questioned. In particular, our deficient knowledge on O exchange between H(2)O and nitrogen oxides during N(2)O production complicates the interpretation of the (18)O signature of N(2)O.Here we studied O exchange during N(2)O formation in soil, using a novel combination of (18)O and (15)N tracing. Twelve soils were studied, covering soil and land-use variability across Europe. All soils demonstrated the significant presence of O exchange, as incorporation of O from (18)O-enriched H(2)O into N(2)O exceeded their maxima achievable through reaction stoichiometry. Based on the retention of the enrichment ratio of (18)O and (15)N of NO(3)(-) into N(2)O, we quantified O exchange during denitrification. Up to 97% (median 85%) of the N(2)O-O originated from H(2)O instead of from the denitrification substrate NO(3)(-).We conclude that in soil, the main source of atmospheric N(2)O, the (18)O signature of N(2)O is mainly determined by H(2)O due to O exchange between nitrogen oxides and H(2)O. This also challenges the assumption that the O of N(2)O originates from O(2) and NO(3)(-), in ratios reflecting reaction stoichiometry.
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Affiliation(s)
- D M Kool
- Alterra, Wageningen University and Research Centre, Wageningen, The Netherlands.
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Morozkina EV, Kurakov AV. Dissimilatory nitrate reduction in fungi under conditions of hypoxia and anoxia: A review. APPL BIOCHEM MICRO+ 2007. [DOI: 10.1134/s0003683807050079] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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15
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Kool DM, Wrage N, Oenema O, Dolfing J, Van Groenigen JW. Oxygen exchange between (de)nitrification intermediates and H2O and its implications for source determination of NO3- and N2O: a review. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2007; 21:3569-3578. [PMID: 17935120 DOI: 10.1002/rcm.3249] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Stable isotope analysis of oxygen (O) is increasingly used to determine the origin of nitrate (NO(3)-) and nitrous oxide (N(2)O) in the environment. The assumption underlying these studies is that the (18)O signature of NO(3)- and N(2)O provides information on the different O sources (O(2) and H(2)O) during the production of these compounds by various biochemical pathways. However, exchange of O atoms between H(2)O and intermediates of the (de)nitrification pathways may change the isotopic signal and thereby bias its interpretation for source determination. Chemical exchange of O between H(2)O and various nitrogenous oxides has been reported, but the probability and extent of its occurrence in terrestrial ecosystems remain unclear. Biochemical O exchange between H(2)O and nitrogenous oxides, NO(2)- in particular, has been reported for monocultures of many nitrifiers and denitrifiers that are abundant in nature, with exchange rates of up to 100%. Therefore, biochemical O exchange is likely to be important in most soil ecosystems, and should be taken into account in source determination studies. Failing to do so might lead to (i) an overestimation of nitrification as NO(3)- source, and (ii) an overestimation of nitrifier denitrification and nitrification-coupled denitrification as N(2)O production pathways. A method to quantify the rate and controls of biochemical O exchange in ecosystems is needed, and we argue this can only be done reliably with artificially enriched (18)O compounds. We conclude that in N source determination studies, the O isotopic signature of especially N(2)O should only be used with extreme caution.
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Affiliation(s)
- D M Kool
- Alterra, Wageningen University and Research Centre, Wageningen, The Netherlands.
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Copeland DM, Soares AS, West AH, Richter-Addo GB. Crystal structures of the nitrite and nitric oxide complexes of horse heart myoglobin. J Inorg Biochem 2006; 100:1413-25. [PMID: 16777231 DOI: 10.1016/j.jinorgbio.2006.04.011] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2006] [Revised: 03/29/2006] [Accepted: 04/14/2006] [Indexed: 11/29/2022]
Abstract
Nitrite is an important species in the global nitrogen cycle, and the nitrite reductase enzymes convert nitrite to nitric oxide (NO). Recently, it has been shown that hemoglobin and myoglobin catalyze the reduction of nitrite to NO under hypoxic conditions. We have determined the 1.20 A resolution crystal structure of the nitrite adduct of ferric horse heart myoglobin (hh Mb). The ligand is bound to iron in the nitrito form, and the complex is formulated as MbIII(ONO-). The Fe-ONO bond length is 1.94 A, and the O-N-O angle is 113 degrees . In addition, the nitrite ligand is stabilized by hydrogen bonding with the distal His64 residue. We have also determined the 1.30 A resolution crystal structures of hh MbIINO. When hh MbIINO is prepared from the reaction of metMbIII with nitrite/dithionite, the FeNO angle is 144 degrees with a Fe-NO bond length of 1.87 A. However, when prepared from the reaction of NO with reduced MbII, the FeNO angle is 120 degrees with a Fe-NO bond length of 2.13 A. This difference in FeNO conformations as a function of preparative method is reproducible, and suggests a role of the distal pocket in hh MbIINO in stabilizing local FeNO conformational minima.
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Affiliation(s)
- Daniel M Copeland
- Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, OK 73019, USA
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17
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Menyailo OV, Hungate BA. Tree species and moisture effects on soil sources of N2O: Quantifying contributions from nitrification and denitrification with18O isotopes. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jg000058] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Oleg V. Menyailo
- Institute of Forest, Siberian Branch of the Russian Academy of Sciences (SB RAS); Krasnoyarsk Russia
| | - Bruce A. Hungate
- Department of Biological Sciences and Merriam-Powell Center for Environmental Research; Northern Arizona University; Flagstaff Arizona USA
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18
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George SJ, Allen JW, Ferguson SJ, Thorneley RN. Time-resolved infrared spectroscopy reveals a stable ferric heme-NO intermediate in the reaction of Paracoccus pantotrophus cytochrome cd1 nitrite reductase with nitrite. J Biol Chem 2000; 275:33231-7. [PMID: 10922371 DOI: 10.1074/jbc.m005033200] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytochrome cd(1) is a respiratory enzyme that catalyzes the physiological one-electron reduction of nitrite to nitric oxide. The enzyme is a dimer, each monomer containing one c-type cytochrome center and one active site d(1) heme. We present stopped-flow Fourier transform infrared data showing the formation of a stable ferric heme d(1)-NO complex (formally d(1)Fe(II)-NO(+)) as a product of the reaction between fully reduced Paracoccus pantotrophus cytochrome cd(1) and nitrite, in the absence of excess reductant. The Fe-(14)NO nu(NO) stretching mode is observed at 1913 cm(-1) with the corresponding Fe-(15)NO band at 1876 cm(-1). This d(1) heme-NO complex is still readily observed after 15 min. EPR and visible absorption spectroscopic data show that within 4 ms of the initiation of the reaction, nitrite is reduced at the d(1) heme, and a cFe(III) d(1)Fe(II)-NO complex is formed. Over the next 100 ms there is an electron redistribution within the enzyme to give a mixed species, 55% cFe(III) d(1)Fe(II)-NO and 45% cFe(II) d(1)Fe(II)-NO(+). No kinetically competent release of NO could be detected, indicating that at least one additional factor is required for product release by the enzyme. Implications for the mechanism of P. pantotrophus cytochrome cd(1) are discussed.
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Affiliation(s)
- S J George
- Biological Chemistry Department, John Innes Centre, Colney Lane, Norwich, NR4 7UH and Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
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19
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Abstract
The structure-function relationships in nitrite reductases, key enzymes in the dissimilatory denitrification pathway which reduce nitrite to nitric oxide (NO), are reviewed in this paper. The mechanisms of NO production are discussed in detail and special attention is paid to new structural information, such as the high resolution structure of the copper- and heme-containing enzymes from different sources. Finally, some implications relevant to regulation of the steady state levels of NO in denitrifiers are presented.
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Affiliation(s)
- F Cutruzzolà
- Dipartimento di Scienze Biochimiche, Università di Roma 'La Sapienza', P.le A. Moro, 5, 00185, Rome, Italy.
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20
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Abstract
Denitrification is a distinct means of energy conservation, making use of N oxides as terminal electron acceptors for cellular bioenergetics under anaerobic, microaerophilic, and occasionally aerobic conditions. The process is an essential branch of the global N cycle, reversing dinitrogen fixation, and is associated with chemolithotrophic, phototrophic, diazotrophic, or organotrophic metabolism but generally not with obligately anaerobic life. Discovered more than a century ago and believed to be exclusively a bacterial trait, denitrification has now been found in halophilic and hyperthermophilic archaea and in the mitochondria of fungi, raising evolutionarily intriguing vistas. Important advances in the biochemical characterization of denitrification and the underlying genetics have been achieved with Pseudomonas stutzeri, Pseudomonas aeruginosa, Paracoccus denitrificans, Ralstonia eutropha, and Rhodobacter sphaeroides. Pseudomonads represent one of the largest assemblies of the denitrifying bacteria within a single genus, favoring their use as model organisms. Around 50 genes are required within a single bacterium to encode the core structures of the denitrification apparatus. Much of the denitrification process of gram-negative bacteria has been found confined to the periplasm, whereas the topology and enzymology of the gram-positive bacteria are less well established. The activation and enzymatic transformation of N oxides is based on the redox chemistry of Fe, Cu, and Mo. Biochemical breakthroughs have included the X-ray structures of the two types of respiratory nitrite reductases and the isolation of the novel enzymes nitric oxide reductase and nitrous oxide reductase, as well as their structural characterization by indirect spectroscopic means. This revealed unexpected relationships among denitrification enzymes and respiratory oxygen reductases. Denitrification is intimately related to fundamental cellular processes that include primary and secondary transport, protein translocation, cytochrome c biogenesis, anaerobic gene regulation, metalloprotein assembly, and the biosynthesis of the cofactors molybdopterin and heme D1. An important class of regulators for the anaerobic expression of the denitrification apparatus are transcription factors of the greater FNR family. Nitrate and nitric oxide, in addition to being respiratory substrates, have been identified as signaling molecules for the induction of distinct N oxide-metabolizing enzymes.
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Affiliation(s)
- W G Zumft
- Lehrstuhl für Mikrobiologie, Universität Fridericiana, Karlsruhe, Germany
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21
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22
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Komeda N, Nagao H, Kushi Y, Adachi GY, Suzuki M, Uehara A, Tanaka K. Molecular Structure of Nitro- and Nitrito-Copper Complexes as Reaction Intermediates in Electrochemical Reduction of Nitrite to Dinitrogen Oxide. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1995. [DOI: 10.1246/bcsj.68.581] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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23
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Ye RW, Averill BA, Tiedje JM. Denitrification: production and consumption of nitric oxide. Appl Environ Microbiol 1994; 60:1053-8. [PMID: 8017903 PMCID: PMC201439 DOI: 10.1128/aem.60.4.1053-1058.1994] [Citation(s) in RCA: 162] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Affiliation(s)
- R W Ye
- Department of Microbiology, Michigan State University, East Lansing 48824
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24
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Jones AM, Hollocher TC. Nitric oxide reductase of Achromobacter cycloclastes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1993. [DOI: 10.1016/0005-2728(93)90121-u] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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25
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Komeda N, Nagao H, Adachi GY, Suzuki M, Uehara A, Tanaka K. Molecular Structure of Copper Nitrito Complex as the Reaction Intermediate of Dissimilatory Reduction of NO2−. CHEM LETT 1993. [DOI: 10.1246/cl.1993.1521] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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26
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Tanimoto T, Hatano KI, Kim DH, Uchiyama H, Shoun H. Co-denitrification by the denitrifying system of the fungusFusarium oxysporum. FEMS Microbiol Lett 1992. [DOI: 10.1111/j.1574-6968.1992.tb05086.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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27
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Baumgärtner M, Conrad R. Role of nitrate and nitrite for production and consumption of nitric oxide during denitrification in soil. FEMS Microbiol Lett 1992. [DOI: 10.1111/j.1574-6968.1992.tb05762.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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28
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H218O isotope exchange studies on the mechanism of reduction of nitric oxide and nitrite to nitrous oxide by denitrifying bacteria. Evidence for an electrophilic nitrosyl during reduction of nitric oxide. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98771-5] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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29
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Goretski J, Hollocher TC. Catalysis of nitrosyl transfer by denitrifying bacteria is facilitated by nitric oxide. Biochem Biophys Res Commun 1991; 175:901-5. [PMID: 2025262 DOI: 10.1016/0006-291x(91)91650-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Two denitrifying bacteria, Pseudomonas stutzeri and Achromobacter cycloclastes, were incubated with Na15NO2 and NaN3 under conditions that allowed catalysis of nitrosyl transfer from nitrite to azide. This transfer, which is presumed to be mediated by the heme- and copper-containing nitrite reductase of P. stutzeri and A. cycloclastes, respectively, leads to formation of isotopically mixed 14,15N2O, whereas denitrification leads to 15N2O. The conditions that emphasized nitrosyl transfer also partially inhibited the nitric oxide reductase system and led to accumulation of 15NO. Absorption of NO from the gas phase by acidic CrSO4 in a sidewell largely abolished nitrosyl transfer to azide. With these two organisms, which are thought to be representative of denitrifiers generally, catalysis of nitrosyl transfer seemed to depend on NO.
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Affiliation(s)
- J Goretski
- Department of Biochemistry, Brandeis University, Waltham, MA 02254
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30
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Bonner FT, Hughes MN, Poole RK, Scott RI. Kinetics of the reactions of trioxodinitrate and nitrite ions with cytochrome d in Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1056:133-8. [PMID: 1847082 DOI: 10.1016/s0005-2728(05)80279-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The rate of reaction of trioxodinitrate with reduced cytochrome oxidase d in membrane particles from Escherichia coli at pH 7 and 25 degrees C depends linearly upon [HN2O3-] over the concentration range studied (up to 0.05 mM) and is also first-order in cytochrome d. The known rate of decomposition of trioxodinitrate to give NO- and NO2- is about 4.5-times faster than the rate of reaction of reduced cytochrome d with trioxodinitrate, implying that cytochrome d reacts directly with NO-, with a trapping ratio of between 0.20 and 0.25, rather than with trioxodinitrate. The implications of the facile formation of the NO(-)-nitrosyl complex of cytochrome d for the mechanism of denitrification are discussed with particular reference to the mechanism of N-N bond formation. The reaction of reduced cytochrome d with nitrite (a decomposition product of trioxodinitrate) under these conditions is much slower than that with trioxodinitrate. The kinetics show a biphasic dependence of initial rate upon nitrite concentration. The rate data at low [NO2-] are consistent with saturation of a high affinity site for nitrite, having Vmax = 4.29.10(-9) M s-1 and Km = 0.034 mM. The existence of two binding sites for nitrite is consistent with the suggestion that the cytochrome bd complex contains two cytochrome d haems.
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Affiliation(s)
- F T Bonner
- Department of Chemistry, King's College London, U.K
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31
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Slemr F, Seiler W. Field study of environmental variables controlling the NO emissions from soil and the NO compensation point. ACTA ACUST UNITED AC 1991. [DOI: 10.1029/91jd01028] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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32
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Goretski J, Hollocher TC. The kinetic and isotopic competence of nitric oxide as an intermediate in denitrification. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)40133-6] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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33
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Heiss B, Frunzke K, Zumft WG. Formation of the N-N bond from nitric oxide by a membrane-bound cytochrome bc complex of nitrate-respiring (denitrifying) Pseudomonas stutzeri. J Bacteriol 1989; 171:3288-97. [PMID: 2542222 PMCID: PMC210048 DOI: 10.1128/jb.171.6.3288-3297.1989] [Citation(s) in RCA: 154] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Nitric oxide (NO) reductase was solubilized by Triton X-100 from the membrane fraction of Pseudomonas stutzeri ZoBell and purified 100-fold to apparent electrophoretic homogeneity. The enzyme consisted of two polypeptides of Mr 38,000 and 17,000 associated with heme b and heme c, respectively. Absorption maxima of the reduced complex were at 420.5, 522.5, and 552.5 nm, with a shoulder at 560 nm. The electron paramagnetic resonance spectrum was characteristic of high- and low-spin ferric heme proteins; no signals typical for iron-sulfur proteins were found. Nitric oxide reductase stoichiometrically transformed NO to nitrous oxide in an ascorbate-phenazine methosulfate-dependent reaction with a specific activity of 11.8 mumols/min per mg of protein. The activity increased to 40 mumols upon the addition of soybean phospholipids, n-octyl-beta-D-glucopyranoside, or its thio derivative to the assay system. Apparent Km values for NO and phenazine methosulfate were 60 and 2 microM, respectively. The pH optimum of the reaction was at 4.8. Cytochrome co was purified from P. stutzeri to permit its distinction from NO reductase. Spectrophotometric binding assays and other criteria also differentiated NO reductase from the respiratory cytochrome bc1 complex.
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Affiliation(s)
- B Heiss
- Lehrstuhl für Mikrobiologie, Universität Karlsruhe, Federal Republic of Germany
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34
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Nitrogen isotopic fractionation and 18O exchange in relation to the mechanism of denitrification of nitrite by Pseudomonas stutzeri. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37696-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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35
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Goretski J, Hollocher TC. Trapping of nitric oxide produced during denitrification by extracellular hemoglobin. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69208-7] [Citation(s) in RCA: 126] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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36
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Ralt D, Wishnok JS, Fitts R, Tannenbaum SR. Bacterial catalysis of nitrosation: involvement of the nar operon of Escherichia coli. J Bacteriol 1988; 170:359-64. [PMID: 3275620 PMCID: PMC210650 DOI: 10.1128/jb.170.1.359-364.1988] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
We have developed a rapid and sensitive fluorimetric method, based on the formation of a fluorescent product from nitrosation of 2,3-diaminonaphthalene, for measuring the ability of bacteria to catalyze nitrosation of amines. We have shown in Escherichia coli that nitrosation can be induced under anaerobic conditions by nitrite and nitrate, that formate is the most efficient electron donor for this reaction, and that nitrosation may be catalyzed by nitrate reductase (EC 1.7.99.4). The narG mutants defective in nitrate reductase do not catalyze nitrosation, and the fnr gene is essential for nitrosation. Induction by nitrite or nitrate of nitrosation, N2O production, and nitrate reductase activity all require the narL gene.
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Affiliation(s)
- D Ralt
- Department of Applied Biological Sciences, Massachusetts Institute of Technology, Cambridge 02139
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37
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38
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Kim CH, Hollocher TC. Catalysis of nitrosyl transfer reactions by a dissimilatory nitrite reductase (cytochrome c,d1). J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43321-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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39
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Bryan BA, Shearer G, Skeeters JL, Kohl DH. Variable expression of the nitrogen isotope effect associated with denitrification of nitrite. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32100-8] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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40
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15N tracer studies on the reduction of nitrite by the purified dissimilatory nitrite reductase of Pseudomonas aeruginosa. Evidence for direct production of N2O without free NO as an intermediate. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32505-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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41
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Garber EA, Wehrli S, Hollocher TC. 15N-tracer and NMR studies on the pathway of denitrification. Evidence against trioxodinitrate but for nitroxyl as an intermediate. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32703-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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42
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Hollocher TC. The pathway of nitrogen and reductive enzymes of denitrification. Antonie Van Leeuwenhoek 1983; 48:531-44. [PMID: 6820251 DOI: 10.1007/bf00399539] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Some recent studies on the pathway of nitrogen and the reductases of denitrification are reviewed. The available evidence suggests that while the intermediates of denitrification can remain enzyme-bound (presumably to nitrite reductase) prior to formation of N2O, NO and nitroxyl (HNO) can be released in part by certain bacteria. Release of NO is recognized by a nitrite/NO-15N exchange reaction and isotopic scrambling in product N2O; release of nitroxyl by Pseudomonas stutzeri is recognized by isotopic scrambling of nitrite and NO in product N2O in absence of exchange and affords evidence that the first N-N bond forms in denitrification at the N1+ redox level. The recent purification and partial characterization of nitrous oxide reductase are described. The ability of the dissimilatory nitrite reductase to activate nitrite for nitrosyl transfer affords a new chemical probe into the mechanism of action of this central enzyme. It would appear that reduction of nitrite is subject to electrophilic catalysis. 18O studies show that dissociation of nitrite from nitrite reductase can be slow relative to competing reduction or nitrosyl transfer.
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