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Josephy T, Kumar R, Bleher K, Röhs F, Glaser T, Rajaraman G, Comba P. Synthesis, Characterization, and Reactivity of Bispidine-Iron(IV)-Tosylimido Species. Inorg Chem 2024; 63:12109-12119. [PMID: 38875304 DOI: 10.1021/acs.inorgchem.4c01237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2024]
Abstract
Reported are the synthesis and detailed studies of the iron(IV)-tosylimido complexes of two isomeric pentadentate bispidine ligands (bispidines are 3,7-diazabicyclo[3.3.1]nonane derivatives). This completes a series of five tosylimido complexes with comparable pentadentate amine/pyridine ligands, where the corresponding [(L)FeIV═O]2+ oxidants have been studied in detail. The characterization of the two new complexes in solution (UV-vis-NIR, Mössbauer, HR-ESI-MS) shows that these oxidants have an intermediate spin (S = 1) electronic ground state. The reactivities have been studied as oxidants in C-H activation at 1,3-cyclohexadiene and nitrogen atom transfer to thioanisole. For the latter substrate, the entire set of data for the five ligands and for both nitrogen and oxygen atom transfer is now available and the interesting observation is that oxygen atom transfer is, as expected, generally faster than nitrogen atom transfer, with the exception of the two ligands that have four and three pyridine groups oriented parallel to the Fe-O and Fe-N axes. A thorough DFT analysis indicates that this is due to steric effects in the case of the [(L)FeIV═O]2+ species, which are less important in the [(L)FeIV═NTs]2+ compounds due to partial electron transfer from the thioanisole substrate to the iron(IV)-tosylimido oxidant.
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Affiliation(s)
- Thomas Josephy
- Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270,Heidelberg D-69120, Germany
| | - Ravi Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Katharina Bleher
- Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270,Heidelberg D-69120, Germany
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen 76344, Germany
| | - Fridolin Röhs
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Thorsten Glaser
- Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstr. 25, Bielefeld D-33615, Germany
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Peter Comba
- Anorganisch-Chemisches Institut, Universität Heidelberg, INF 270,Heidelberg D-69120, Germany
- Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), Universität Heidelberg, Heidelberg 69120, Germany
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2
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Ye J, Hu A, Gao C, Li F, Li L, Guo Y, Ren G, Li B, Rensing C, Nealson KH, Zhou S, Xiong Y. Abiotic Methane Production Driven by Ubiquitous Non-Fenton-Type Reactive Oxygen Species. Angew Chem Int Ed Engl 2024; 63:e202403884. [PMID: 38489233 DOI: 10.1002/anie.202403884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2024] [Revised: 03/15/2024] [Accepted: 03/15/2024] [Indexed: 03/17/2024]
Abstract
Abiotic CH4 production driven by Fenton-type reactive oxygen species (ROS) has been confirmed to be an indispensable component of the atmospheric CH4 budget. While the chemical reactions independent of Fenton chemistry to ROS are ubiquitous in nature, it remains unknown whether the produced ROS can drive abiotic CH4 production. Here, we first demonstrated the abiotic CH4 production at the soil-water interface under illumination. Leveraging this finding, polymeric carbon nitrides (CNx) as a typical analogue of natural geobattery material and dimethyl sulfoxide (DMSO) as a natural methyl donor were used to unravel the underlying mechanisms. We revealed that the ROS, photocatalytically produced by CNx, can oxidize DMSO into CH4 with a high selectivity of 91.5 %. Such an abiotic CH4 production process was further expanded to various non-Fenton-type reaction systems, such as electrocatalysis, pyrocatalysis and sonocatalysis. This work provides insights into the geochemical cycle of abiotic CH4, and offers a new route to CH4 production via integrated energy development.
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Affiliation(s)
- Jie Ye
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Andong Hu
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Chao Gao
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, 230026, China
| | - Fengqi Li
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Lei Li
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yulin Guo
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Guoping Ren
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Bing Li
- Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Christopher Rensing
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Kenneth H Nealson
- Department of Earth Science, University of Southern California, Los Angeles, California, 90089, United States
| | - Shungui Zhou
- Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, 350002, China
| | - Yujie Xiong
- School of Chemistry and Materials Science, University of Science and Technology of China, Hefei, 230026, China
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3
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Mao Y, Lin T, Li H, He R, Ye K, Yu W, He Q. Aerobic methane production by phytoplankton as an important methane source of aquatic ecosystems: Reconsidering the global methane budget. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 907:167864. [PMID: 37866611 DOI: 10.1016/j.scitotenv.2023.167864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 10/09/2023] [Accepted: 10/13/2023] [Indexed: 10/24/2023]
Abstract
Biological methane, a major source of global methane budget, is traditionally thought to be produced in anaerobic environments. However, the recent reports about methane supersaturation occurring in oxygenated water layer, termed as "methane paradox", have challenged this prevailing paradigm. Significantly, growing evidence has indicated that phytoplankton including prokaryotic cyanobacteria and eukaryotic algae are capable of generating methane under aerobic conditions. In this regard, a systematic review of aerobic methane production by phytoplankton is expected to arouse the public attention, contributing to the understanding of methane paradox. Here, we comprehensively summarize the widespread phenomena of methane supersaturation in oxic layers. The remarkable correlation relationships between methane concentration and several key indicators (depth, chlorophyll a level and organic sulfide concentration) indicate the significance of phytoplankton in in-situ methane accumulation. Subsequently, four mechanisms of aerobic methane production by phytoplankton are illustrated in detail, including photosynthesis-driven metabolism, reactive oxygen species (ROS)-driven demethylation of methyl donors, methanogenesis catalyzed by nitrogenase and demethylation of phosphonates catalyzed by CP lyase. The first two pathways occur in various phytoplankton, while the latter two have been specially discovered in cyanobacteria. Additionally, the effects of four crucial factors on aerobic methane production by phytoplankton are also discussed, including phytoplankton species, light, temperature and crucial nutrients. Finally, the measures to control global methane emissions from phytoplankton, the precise intracellular mechanisms of methane production and a more complete global methane budget model are definitely required in the future research on methane production by phytoplankton. This review would provide guidance for future studies of aerobic methane production by phytoplankton and emphasize the potential contribution of aquatic ecosystems to global methane budget.
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Affiliation(s)
- Yufeng Mao
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China; Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China; Lingzhi Environmental Protection Co., Ltd, Wuxi 214200, China
| | - Tong Lin
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Hong Li
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China
| | - Ruixu He
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China
| | - Kailai Ye
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China
| | - Weiwei Yu
- Key Laboratory of Hydraulic and Waterway Engineering, Ministry of Education, Chongqing Jiaotong University, Chongqing 400074, China
| | - Qiang He
- Key Laboratory of Eco-Environment of Three Gorges Region, Ministry of Education, Chongqing University, Chongqing 400044, China.
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Kohl L, Tenhovirta SAM, Koskinen M, Putkinen A, Haikarainen I, Polvinen T, Galeotti L, Mammarella I, Siljanen HMP, Robson TM, Adamczyk B, Pihlatie M. Radiation and temperature drive diurnal variation of aerobic methane emissions from Scots pine canopy. Proc Natl Acad Sci U S A 2023; 120:e2308516120. [PMID: 38127980 PMCID: PMC10756279 DOI: 10.1073/pnas.2308516120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 10/29/2023] [Indexed: 12/23/2023] Open
Abstract
Methane emissions from plant foliage may play an important role in the global methane cycle, but their size and the underlying source processes remain poorly understood. Here, we quantify methane fluxes from the shoots of Scots pine trees, a dominant tree species in boreal forests, to identify source processes and environmental drivers, and we evaluate whether these fluxes can be constrained at the ecosystem-level by eddy covariance flux measurements. We show that shoot-level measurements conducted in forest, garden, or greenhouse settings; on mature trees and saplings; manually and with an automated CO2-, temperature-, and water-controlled chamber system; and with multiple methane analyzers all resulted in comparable daytime fluxes (0.144 ± 0.019 to 0.375 ± 0.074 nmol CH4 g-1 foliar d.w. h-1). We further find that these emissions exhibit a pronounced diurnal cycle that closely follows photosynthetically active radiation and is further modulated by temperature. These diurnal patterns indicate that methane production is associated with diurnal cycle of sunlight, indicating that this production is either a byproduct of photosynthesis-associated biochemical reactions (e.g., the methionine cycle) or produced through nonenzymatic photochemical reactions in plant biomass. Moreover, we identified a light-dependent component in stand-level methane fluxes, which showed order-of-magnitude agreement with shoot-level measurements (0.968 ± 0.031 nmol CH4 g-1 h-1) and which provides an upper limit for shoot methane emissions.
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Affiliation(s)
- Lukas Kohl
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio70600, Finland
| | - Salla A. M. Tenhovirta
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
| | - Markku Koskinen
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
| | - Anuliina Putkinen
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Department of Microbiology, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
| | - Iikka Haikarainen
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
| | - Tatu Polvinen
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
| | - Luca Galeotti
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
| | - Ivan Mammarella
- Institute for Atmosphere and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki00560, Finland
| | - Henri M. P. Siljanen
- Department of Environmental and Biological Sciences, University of Eastern Finland, Kuopio70600, Finland
- Archaea Biology and Ecogenomics Unit, Department of Functional and Evolutionary Ecology, University of Vienna, Vienna1030, Austria
| | - Thomas Matthew Robson
- National School of Forestry, University of Cumbria, AmblesideLA22 9BB, United Kingdom
- Organismal and Evolutionary Biology (OEB), Faculty of Biological and Environmental Science, University of Helsinki, Helsinki00790, Finland
| | - Bartosz Adamczyk
- Natural Resources Institute Finland (Luke), Helsinki00790, Finland
| | - Mari Pihlatie
- Department of Agricultural Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Institute for Atmosphere and Earth System Research/Forest Sciences, Faculty of Agriculture and Forestry, University of Helsinki, Helsinki00790, Finland
- Viikki Plant Science Center, University of Helsinki, Helsinki00790, Finland
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5
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Schroll M, Liu L, Einzmann T, Keppler F, Grossart HP. Methane accumulation and its potential precursor compounds in the oxic surface water layer of two contrasting stratified lakes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 903:166205. [PMID: 37567306 DOI: 10.1016/j.scitotenv.2023.166205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 08/08/2023] [Accepted: 08/08/2023] [Indexed: 08/13/2023]
Abstract
Methane (CH4) supersaturation in oxygenated waters is a widespread phenomenon despite the traditional perception of strict anoxic methanogenesis. This notion has recently been challenged by successive findings of processes and mechanisms that produce CH4 in oxic environments. While some of the processes contributing to the vertical accumulation of CH4 in the oxygenated upper water layers of freshwater lakes have been identified, temporal variations as well as drivers are still poorly understood. In this study, we investigated the accumulation of CH4 in oxic water layers of two contrasting lakes in Germany: Lake Willersinnweiher (shallow, monomictic, eutrophic) and Lake Stechlin (deep, dimictic, eutrophic) from 2019 to 2020. The dynamics of isotopic values of CH4 and the role of potential precursor compounds of oxic CH4 production were explored. During the study period, persistent strong CH4 supersaturation (relative to air) was observed in the surface waters, mostly concentrated around the thermocline. The magnitude of vertical CH4 accumulation strongly varied over season and was generally more pronounced in shallow Lake Willersinnweiher. In both lakes, increases in CH4 concentrations from the surface to the thermocline mostly coincided with an enrichment in 13C-CH4 and 2H-CH4, indicating a complex interaction of multiple processes such as CH4 oxidation, CH4 transport from littoral sediments and oxic CH4 production, sustaining and controlling this CH4 supersaturation. Furthermore, incubation experiments with 13C- and 2H-labelled methylated P-, N- and C- compounds clearly showed that methylphosphonate, methylamine and methionine acted as potent precursors of accumulating CH4 and at least partly sustained CH4 supersaturation. This highlights the need to better understand the mechanisms underlying CH4 accumulation by focusing on production and transport pathways of CH4 and its precursor compounds, e.g., produced via phytoplankton. Such knowledge forms the foundation to better predict aquatic CH4 dynamics and its subsequent rates of emission to the atmosphere.
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Affiliation(s)
- Moritz Schroll
- Laboratory of Plateau Geographical Processes and Environmental Changes, Faculty of Geography, Yunnan Normal University, 650500 Kunming, China; Institute of Earth Sciences, Heidelberg University, 69120 Heidelberg, Germany.
| | - Liu Liu
- Laboratory of Plateau Geographical Processes and Environmental Changes, Faculty of Geography, Yunnan Normal University, 650500 Kunming, China; Department of Plankton and Microbial Ecology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, 16775 Stechlin, Germany.
| | - Teresa Einzmann
- Institute of Earth Sciences, Heidelberg University, 69120 Heidelberg, Germany; Department of Environmental Sciences, University of Basel, Basel, Switzerland
| | - Frank Keppler
- Institute of Earth Sciences, Heidelberg University, 69120 Heidelberg, Germany; Heidelberg Center for the Environment (HCE), Heidelberg University, 69120 Heidelberg, Germany
| | - Hans-Peter Grossart
- Department of Plankton and Microbial Ecology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, 16775 Stechlin, Germany; Institute of Biochemistry and Biology, Potsdam University, 14476 Potsdam, Germany
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6
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Hädeler J, Velmurugan G, Lauer R, Radhamani R, Keppler F, Comba P. Natural Abiotic Iron-Oxido-Mediated Formation of C 1 and C 2 Compounds from Environmentally Important Methyl-Substituted Substrates. J Am Chem Soc 2023. [PMID: 37930326 DOI: 10.1021/jacs.3c06709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Organic and inorganic volatile compounds containing one carbon atom (C1), such as carbon dioxide, methane, methanol, formaldehyde, carbon monoxide, and chloromethane, are ubiquitous in the environment, are key components in global carbon cycling, play an important role in atmospheric physics and chemistry, e.g., as greenhouse gases, destroy stratospheric and tropospheric ozone, and control the atmospheric oxidation capacity. Up to now, most C1 compounds in the environment were associated with complex metabolic and enzymatic pathways in organisms or to combustion processes of organic matter. We now present compelling evidence that many C1 and C2 compounds have a common origin in methyl groups of methyl-substituted substrates that are cleaved by the iron oxide-mediated formation of methyl radicals. This scenario is derived from experiments with a mechanistically well-studied bispidine-iron-oxido complex as oxidant and dimethyl sulfoxide as the environmentally relevant model substrate and is supported by computational modeling based on density functional theory and ab initio quantum-chemical studies. The exhaustive experimental model studies, also involving extensive isotope labeling, are complemented with the substitution of the bispidine model system by environmentally relevant iron oxides and, finally, a collection of soils with varying iron and organic matter contents. The combination of all data suggests that the iron oxide-mediated formation of methyl radicals from methyl-substituted substrates is a common abiotic source for widespread C1 and C2 compounds in the environment.
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Affiliation(s)
- Jonas Hädeler
- Institut für Geowissenschaften, INF 234-236, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Gunasekaran Velmurugan
- Anorganisch-Chemisches Institut INF 270, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Rebekka Lauer
- Institut für Geowissenschaften, INF 234-236, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Rejith Radhamani
- Anorganisch-Chemisches Institut INF 270, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Frank Keppler
- Institut für Geowissenschaften, INF 234-236, Universität Heidelberg, D-69120 Heidelberg, Germany
- Heidelberg Center for the Environment (HCE), Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Peter Comba
- Anorganisch-Chemisches Institut INF 270, Universität Heidelberg, D-69120 Heidelberg, Germany
- Interdisciplinary Center for Scientific Computing, INF 205, Universität Heidelberg, D-69120 Heidelberg, Germany
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7
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Ernst L, Barayeu U, Hädeler J, Dick TP, Klatt JM, Keppler F, Rebelein JG. Methane formation driven by light and heat prior to the origin of life and beyond. Nat Commun 2023; 14:4364. [PMID: 37528079 PMCID: PMC10394037 DOI: 10.1038/s41467-023-39917-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 07/03/2023] [Indexed: 08/03/2023] Open
Abstract
Methane is a potent greenhouse gas, which likely enabled the evolution of life by keeping the early Earth warm. Here, we demonstrate routes towards abiotic methane and ethane formation under early-earth conditions from methylated sulfur and nitrogen compounds with prebiotic origin. These compounds are demethylated in Fenton reactions governed by ferrous iron and reactive oxygen species (ROS) produced by light and heat in aqueous environments. After the emergence of life, this phenomenon would have greatly intensified in the anoxic Archean by providing methylated sulfur and nitrogen substrates. This ROS-driven Fenton chemistry can occur delocalized from serpentinization across Earth's humid realm and thereby substantially differs from previously suggested methane formation routes that are spatially restricted. Here, we report that Fenton reactions driven by light and heat release methane and ethane and might have shaped the chemical evolution of the atmosphere prior to the origin of life and beyond.
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Affiliation(s)
- Leonard Ernst
- Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
- Center for Synthetic Microbiology (SYNMIKRO), 35032, Marburg, Germany.
| | - Uladzimir Barayeu
- Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Jonas Hädeler
- Institute of Earth Sciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Tobias P Dick
- Division of Redox Regulation, German Cancer Research Center (DKFZ), DKFZ-ZMBH Alliance, 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69120, Heidelberg, Germany
| | - Judith M Klatt
- Center for Synthetic Microbiology (SYNMIKRO), 35032, Marburg, Germany
- Microcosm Earth Center, Max Planck Institute for Terrestrial Microbiology & Philipps University Marburg, 35032, Marburg, Germany
- Biogeochemistry Group, Department for Chemistry, Philipps University Marburg, 35032, Marburg, Germany
| | - Frank Keppler
- Institute of Earth Sciences, Heidelberg University, 69120, Heidelberg, Germany
- Heidelberg Center for the Environment HCE, Heidelberg University, 69120, Heidelberg, Germany
| | - Johannes G Rebelein
- Max Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
- Center for Synthetic Microbiology (SYNMIKRO), 35032, Marburg, Germany.
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8
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Keppler F, Boros M, Polag D. Radical-Driven Methane Formation in Humans Evidenced by Exogenous Isotope-Labeled DMSO and Methionine. Antioxidants (Basel) 2023; 12:1381. [PMID: 37507920 PMCID: PMC10376501 DOI: 10.3390/antiox12071381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 06/29/2023] [Accepted: 07/01/2023] [Indexed: 07/30/2023] Open
Abstract
Methane (CH4), which is produced endogenously in animals and plants, was recently suggested to play a role in cellular physiology, potentially influencing the signaling pathways and regulatory mechanisms involved in nitrosative and oxidative stress responses. In addition, it was proposed that the supplementation of CH4 to organisms may be beneficial for the treatment of several diseases, including ischemia, reperfusion injury, and inflammation. However, it is still unclear whether and how CH4 is produced in mammalian cells without the help of microorganisms, and how CH4 might be involved in physiological processes in humans. In this study, we produced the first evidence of the principle that CH4 is formed non-microbially in the human body by applying isotopically labeled methylated sulfur compounds, such as dimethyl sulfoxide (DMSO) and methionine, as carbon precursors to confirm cellular CH4 formation. A volunteer applied isotopically labeled (2H and 13C) DMSO on the skin, orally, and to blood samples. The monitoring of stable isotope values of CH4 convincingly showed the conversion of the methyl groups, as isotopically labeled CH4 was formed during all experiments. Based on these results, we considered several hypotheses about endogenously formed CH4 in humans, including physiological aspects and stress responses involving reactive oxygen species (ROS). While further and broader validation studies are needed, the results may unambiguously serve as a proof of concept for the endogenous formation of CH4 in humans via a radical-driven process. Furthermore, these results might encourage follow-up studies to decipher the potential physiological role of CH4 and its bioactivity in humans in more detail. Of particular importance is the potential to monitor CH4 as an oxidative stress biomarker if the observed large variability of CH4 in breath air is an indicator of physiological stress responses and immune reactions. Finally, the potential role of DMSO as a radical scavenger to counteract oxidative stress caused by ROS might be considered in the health sciences. DMSO has already been investigated for many years, but its potential positive role in medical use remains highly uncertain.
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Affiliation(s)
- Frank Keppler
- Institute of Earth Sciences, Heidelberg University, D-69120 Heidelberg, Germany
- Heidelberg Center for the Environment (HCE), Heidelberg University, D-69120 Heidelberg, Germany
| | - Mihály Boros
- Institute of Surgical Research, University of Szeged, H-6724 Szeged, Hungary
| | - Daniela Polag
- Institute of Earth Sciences, Heidelberg University, D-69120 Heidelberg, Germany
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9
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Bleher K, Comba P, Kass D, Ray K, Wadepohl H. Reactivities of iron(IV)-oxido compounds with pentadentate bispidine ligands. J Inorg Biochem 2023; 241:112123. [PMID: 36701984 DOI: 10.1016/j.jinorgbio.2023.112123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 01/05/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023]
Abstract
The FeIVO complexes of bispidines (3,7-diazabicyclo[3.3.1]nonane derivatives) are known to be highly reactive oxidants - with the tetradentate bispidine, the so far most reactive ferryl complex has been reported and two isomeric pentadentate ligands also lead to very reactive high-valent oxidants. With a series of 4 new bispidine derivatives we now try to address the question why the bispidine scaffold in general leads to very reactive oxidants and how this can be tuned by ligand modifications. The study is based on a full structural, spectroscopic and electrochemical analysis of the iron(II) precursors, spectroscopic data of the iron(IV)-oxido complexes, a kinetic analysis of the stoichiometric oxidation of thioanisole by five different bispidine‑iron(IV)-oxido complexes and on product analyses of reactions by the five ferryl oxidants with thioanisole, β-methylstyrene and cis-stilbene as substrates.
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Affiliation(s)
- Katharina Bleher
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany
| | - Peter Comba
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany; Universität Heidelberg, Interdisziplinäres Zentrum für Wissenschaftliches Rechnen (IWR), Germany.
| | - Dustin Kass
- Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor Strasse 2, D-12489 Berlin, Germany
| | - Kallol Ray
- Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor Strasse 2, D-12489 Berlin, Germany
| | - Hubert Wadepohl
- Universität Heidelberg, Anorganisch-Chemisches Institut, INF 270, D-69120 Heidelberg, Germany
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10
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Zhao Z, Li M, Du N, Li Z, Zhang Y, Zhang Q. Fenton-like reaction of glucose oxidase-glucose@Kaolin coupled with green rust: A framework triggering FeⅣ=O in refractory pollutants degradation. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.122061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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11
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Schroll M, Lenhart K, Greiner S, Keppler F. Making plant methane formation visible-Insights from application of 13C-labeled dimethyl sulfoxide. PLANT-ENVIRONMENT INTERACTIONS (HOBOKEN, N.J.) 2022; 3:104-117. [PMID: 37284426 PMCID: PMC10168057 DOI: 10.1002/pei3.10076] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 04/06/2022] [Accepted: 04/15/2022] [Indexed: 06/08/2023]
Abstract
Methane (CH4) formation by vegetation has been studied intensively over the last 15 years. However, reported CH4 emissions vary by several orders of magnitude, thus making global estimates difficult. Moreover, the mechanism(s) for CH4 formation by plants is (are) largely unknown.Here, we introduce a new approach for making CH4 formation by plants clearly visible. By application of 13C-labeled dimethyl sulfoxide (DMSO) onto the leaves of tobacco plants (Nicotiana tabacum) and Chinese silver grass (Miscanthus sinensis) the effect of light and dark conditions on CH4 formation of this pathway was examined by monitoring stable carbon isotope ratios of headspace CH4 (δ13C-CH4 values).Both plant species showed increasing headspace δ13C-CH4 values while exposed to light. Higher light intensities increased CH4 formation rates in N. tabacum but decreased rates for M. sinensis. In the dark no formation of CH4 could be detected for N. tabacum, while M. sinensis still produced ~50% of CH4 compared to that during light exposure.Our findings suggest that CH4 formation is clearly dependent on light conditions and plant species and thus indicate that DMSO is a potential precursor of vegetative CH4. The novel isotope approach has great potential to investigate, at high temporal resolution, physiological, and environmental factors that control pathway-specific CH4 emissions from plants.
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Affiliation(s)
- Moritz Schroll
- Institute of Earth SciencesHeidelberg UniversityHeidelbergGermany
| | - Katharina Lenhart
- Bingen University of Applied SciencesBingenGermany
- Center for Organismal Studies (COS)HeidelbergGermany
| | | | - Frank Keppler
- Institute of Earth SciencesHeidelberg UniversityHeidelbergGermany
- Heidelberg Center for the Environment (HCE)Heidelberg UniversityHeidelbergGermany
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12
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Liu LY, Xie GJ, Ding J, Liu BF, Xing DF, Ren NQ, Wang Q. Microbial methane emissions from the non-methanogenesis processes: A critical review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151362. [PMID: 34740653 DOI: 10.1016/j.scitotenv.2021.151362] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/28/2021] [Accepted: 10/28/2021] [Indexed: 06/13/2023]
Abstract
Methane, a potent greenhouse gas of global importance, has traditionally been considered as an end product of microbial methanogenesis of organic matter. Paradoxically, growing evidence has shown that some microbes, such as cyanobacteria, algae, fungi, purple non-sulfur bacteria, and cryptogamic covers, produce methane in oxygen-saturated aquatic and terrestrial ecosystems. The non-methanogenesis process could be an important potential contributor to methane emissions. This systematic review summarizes the knowledge of microorganisms involved in the non-methanogenesis process and the possible mechanisms of methane formation. Cyanobacteria-derived methane production may be attributed to either demethylation of methyl phosphonates or linked to light-driven primary productivity, while algae produce methane by utilizing methylated sulfur compounds as possible carbon precursors. In addition, fungi produce methane by utilizing methionine as a possible carbon precursor, and purple non-sulfur bacteria reduce carbon dioxide to methane by nitrogenase. The microbial methane distribution from the non-methanogenesis processes in aquatic and terrestrial environments and its environmental significance to global methane emissions, possible mechanisms of methane production in each open water, water-to-air methane fluxes, and the impact of climate change on microorganisms are also discussed. Finally, future perspectives are highlighted, such as establishing more in-situ experiments, quantifying methane flux through optimizing empirical models, distinguishing individual methane sources, and investigating nitrogenase-like enzyme systems to improve our understanding of microbial methane emission from the non-methanogenesis process.
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Affiliation(s)
- Lu-Yao Liu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Guo-Jun Xie
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
| | - Jie Ding
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Bing-Feng Liu
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - De-Feng Xing
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Nan-Qi Ren
- State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China
| | - Qilin Wang
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
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13
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Latifi R, Palluccio TD, Ye W, Minnick JL, Glinton KS, Rybak-Akimova EV, de Visser SP, Tahsini L. pH Changes That Induce an Axial Ligand Effect on Nonheme Iron(IV) Oxo Complexes with an Appended Aminopropyl Functionality. Inorg Chem 2021; 60:13821-13832. [PMID: 34291939 DOI: 10.1021/acs.inorgchem.1c01312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nonheme iron enzymes often utilize a high-valent iron(IV) oxo species for the biosynthesis of natural products, but their high reactivity often precludes structural and functional studies of these complexes. In this work, a combined experimental and computational study is presented on a biomimetic nonheme iron(IV) oxo complex bearing an aminopyridine macrocyclic ligand and its reactivity toward olefin epoxidation upon changes in the identity and coordination ability of the axial ligand. Herein, we show a dramatic effect of the pH on the oxygen-atom-transfer (OAT) reaction with substrates. In particular, these changes have occurred because of protonation of the axial-bound pendant amine group, where its coordination to iron is replaced by a solvent molecule or anionic ligand. This axial ligand effect influences the catalysis, and we observe enhanced cyclooctene epoxidation yields and turnover numbers in the presence of the unbound protonated pendant amine group. Density functional theory studies were performed to support the experiments and highlight that replacement of the pendant amine with a neutral or anionic ligand dramatically lowers the rate-determining barriers of cyclooctene epoxidation. The computational work further establishes that the change in OAT is due to electrostatic interactions of the pendant amine cation that favorably affect the barrier heights.
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Affiliation(s)
- Reza Latifi
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Taryn D Palluccio
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Wanhua Ye
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Jennifer L Minnick
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Kwame S Glinton
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Elena V Rybak-Akimova
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Sam P de Visser
- Manchester Institute of Biotechnology and Department of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M1 7DN, United Kingdom
| | - Laleh Tahsini
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
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14
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Martel AB, Taylor AE, Qaderi MM. Individual and interactive effects of temperature and light intensity on canola growth, physiological characteristics and methane emissions. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2020; 157:160-168. [PMID: 33120108 DOI: 10.1016/j.plaphy.2020.10.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 10/17/2020] [Indexed: 06/11/2023]
Abstract
Earlier studies have shown that plants produce methane (CH4) under aerobic conditions, and that this emission is not microbial in nature. However, the precursors of aerobic CH4 remain under debate, and the combined effects of environmental factors on plant-derived CH4 requires further attention. The objective of this study was to determine the interactive effects of temperature and light intensity on CH4 and other relevant plant parameters in canola (Brassica napus L.). Plants were grown under two temperature regimes (22/18 °C and 28/24 °C, 16 h light/8 h dark) and two light intensities (300 and 600 μmol photons m-2 s-1) for 21 days after one week of growth under 22/18 °C (16 h light/8 h dark). In this study, higher temperature had little effects on CH4 emissions from plants, indicating the mitigating effects of higher light intensity. Higher light intensity, however, significantly decreased CH4, which was inversely related to plant dry mass. Higher light intensity decreased stem height, leaf area ratio, chlorophyll, nitrogen balance index, leaf moisture, methionine (Met) and ethylene (C2H4), but increased specific leaf mass, photochemical quenching, flavonoids, epicuticular wax, lysine and tyrosine. The results revealed that increased CH4 emissions from plants could be related to changes in plant physiological activities, which portrayed themselves in increased C2H4 evolution, and methylated amino acids, such as Met. We conclude that higher light intensity reduces Met and, in turn, CH4 and C2H4 emissions, but lower light intensity enhances CH4 formation through cleavage of methyl group of amino acids by reactive oxygen species, as previously suggested.
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Affiliation(s)
- Ashley B Martel
- Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada
| | - Amanda E Taylor
- Department of Biology, Mount Saint Vincent University, 166 Bedford Highway, Halifax, Nova Scotia, B3M 2J6, Canada
| | - Mirwais M Qaderi
- Department of Biology, Saint Mary's University, 923 Robie Street, Halifax, Nova Scotia, B3H 3C3, Canada; Department of Biology, Mount Saint Vincent University, 166 Bedford Highway, Halifax, Nova Scotia, B3M 2J6, Canada.
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15
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Ansari M, Senthilnathan D, Rajaraman G. Deciphering the origin of million-fold reactivity observed for the open core diiron [HO-Fe III-O-Fe IV[double bond, length as m-dash]O] 2+ species towards C-H bond activation: role of spin-states, spin-coupling, and spin-cooperation. Chem Sci 2020; 11:10669-10687. [PMID: 33209248 PMCID: PMC7654192 DOI: 10.1039/d0sc02624g] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 06/16/2020] [Indexed: 01/26/2023] Open
Abstract
High-valent metal-oxo species have been characterised as key intermediates in both heme and non-heme enzymes that are found to perform efficient aliphatic hydroxylation, epoxidation, halogenation, and dehydrogenation reactions. Several biomimetic model complexes have been synthesised over the years to mimic both the structure and function of metalloenzymes. The diamond-core [Fe2(μ-O)2] is one of the celebrated models in this context as this has been proposed as the catalytically active species in soluble methane monooxygenase enzymes (sMMO), which perform the challenging chemical conversion of methane to methanol at ease. In this context, a report of open core [HO(L)FeIII-O-FeIV(O)(L)]2+ (1) gains attention as this activates C-H bonds a million-fold faster compared to the diamond-core structure and has the dual catalytic ability to perform hydroxylation as well as desaturation with organic substrates. In this study, we have employed density functional methods to probe the origin of the very high reactivity observed for this complex and also to shed light on how this complex performs efficient hydroxylation and desaturation of alkanes. By modelling fifteen possible spin-states for 1 that could potentially participate in the reaction mechanism, our calculations reveal a doublet ground state for 1 arising from antiferromagnetic coupling between the quartet FeIV centre and the sextet FeIII centre, which regulates the reactivity of this species. The unusual stabilisation of the high-spin ground state for FeIV[double bond, length as m-dash]O is due to the strong overlap of with the orbital, reducing the antibonding interactions via spin-cooperation. The electronic structure features computed for 1 are consistent with experiments offering confidence in the methodology chosen. Further, we have probed various mechanistic pathways for the C-H bond activation as well as -OH rebound/desaturation of alkanes. An extremely small barrier height computed for the first hydrogen atom abstraction by the terminal FeIV[double bond, length as m-dash]O unit was found to be responsible for the million-fold activation observed in the experiments. The barrier height computed for -OH rebound by the FeIII-OH unit is also smaller suggesting a facile hydroxylation of organic substrates by 1. A strong spin-cooperation between the two iron centres also reduces the barrier for second hydrogen atom abstraction, thus making the desaturation pathway competitive. Both the spin-state as well as spin-coupling between the two metal centres play a crucial role in dictating the reactivity for species 1. By exploring various mechanistic pathways, our study unveils the fact that the bridged μ-oxo group is a poor electrophile for both C-H activation as well for -OH rebound. As more and more evidence is gathered in recent years for the open core geometry of sMMO enzymes, the idea of enhancing the reactivity via an open-core motif has far-reaching consequences.
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Affiliation(s)
- Mursaleem Ansari
- Department of Chemistry , Indian Institute of Technology Bombay , Mumbai 400076 , India .
| | - Dhurairajan Senthilnathan
- Center for Computational Chemistry , CRD , PRIST University , Vallam , Thanjavur , Tamilnadu 613403 , India
| | - Gopalan Rajaraman
- Department of Chemistry , Indian Institute of Technology Bombay , Mumbai 400076 , India .
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16
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Boros M, Keppler F. Methane Production and Bioactivity-A Link to Oxido-Reductive Stress. Front Physiol 2019; 10:1244. [PMID: 31611816 PMCID: PMC6776796 DOI: 10.3389/fphys.2019.01244] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 09/10/2019] [Indexed: 12/15/2022] Open
Abstract
Biological methane formation is associated with anoxic environments and the activity of anaerobic prokaryotes (Archaea). However, recent studies have confirmed methane release from eukaryotes, including plants, fungi, and animals, even in the absence of microbes and in the presence of oxygen. Furthermore, it was found that aerobic methane emission in plants is stimulated by a variety of environmental stress factors, leading to reactive oxygen species (ROS) generation. Further research presented evidence that molecules with sulfur and nitrogen bonded methyl groups such as methionine or choline are carbon precursors of aerobic methane formation. Once generated, methane is widely considered to be physiologically inert in eukaryotes, but several studies have found association between mammalian methanogenesis and gastrointestinal (GI) motility changes. In addition, a number of recent reports demonstrated anti-inflammatory potential for exogenous methane-based approaches in model anoxia-reoxygenation experiments. It has also been convincingly demonstrated that methane can influence the downstream effectors of transiently increased ROS levels, including mitochondria-related pro-apoptotic pathways during ischemia-reperfusion (IR) conditions. Besides, exogenous methane can modify the outcome of gasotransmitter-mediated events in plants, and it appears that similar mechanism might be active in mammals as well. This review summarizes the relevant literature on methane-producing processes in eukaryotes, and the available results that underscore its bioactivity. The current evidences suggest that methane liberation and biological effectiveness are both linked to cellular redox regulation. The data collectively imply that exogenous methane influences the regulatory mechanisms and signaling pathways involved in oxidative and nitrosative stress responses, which suggests a modulator role for methane in hypoxia-linked pathologies.
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Affiliation(s)
- Mihály Boros
- Institute of Surgical Research, Interdisciplinary Centre of Excellence, University of Szeged, Szeged, Hungary
| | - Frank Keppler
- Institute of Earth Sciences, Heidelberg University, Heidelberg, Germany
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17
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Day TA, Bliss MS, Placek SK, Tomes AR, Guénon R. Thermal abiotic emission of
CO
2
and
CH
4
from leaf litter and its significance in a photodegradation assessment. Ecosphere 2019. [DOI: 10.1002/ecs2.2745] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Affiliation(s)
- Thomas A. Day
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA
| | - Michael S. Bliss
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA
| | - Sarah K. Placek
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA
| | - Alexander R. Tomes
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA
| | - René Guénon
- School of Life Sciences Arizona State University Tempe Arizona 85287 USA
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18
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Comba P, Faltermeier D, Gieger S, Keppler F, Schöler HF, Schroll M. Iron catalyzed demethylation of acetic acid*. J COORD CHEM 2018. [DOI: 10.1080/00958972.2018.1490414] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Peter Comba
- Anorganisch-Chemisches Institut and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Dieter Faltermeier
- Anorganisch-Chemisches Institut and Interdisciplinary Center for Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Sascha Gieger
- Institute of Earth Sciences and Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany
| | - Frank Keppler
- Institute of Earth Sciences and Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany
| | - Heinz Friedrich Schöler
- Institute of Earth Sciences and Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany
| | - Moritz Schroll
- Institute of Earth Sciences and Heidelberg Center for the Environment (HCE), Heidelberg University, Heidelberg, Germany
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19
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Polag D, Keppler F. Long-term monitoring of breath methane. THE SCIENCE OF THE TOTAL ENVIRONMENT 2018; 624:69-77. [PMID: 29247906 DOI: 10.1016/j.scitotenv.2017.12.097] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 12/08/2017] [Accepted: 12/08/2017] [Indexed: 06/07/2023]
Abstract
In recent years, methane as a component of exhaled human breath has been considered as a potential bioindicator providing information on microbial activity in the intestinal tract. Several studies indicated a relationship between breath methane status and specific gastrointestinal disease. So far, almost no attention has been given to the temporal variability of breath methane production by individual persons. Thus here, for the first time, long-term monitoring was carried out measuring breath methane of three volunteers over periods between 196 and 1002days. Results were evaluated taking into consideration the health status and specific medical intervention events for each individual during the monitoring period, and included a gastroscopy procedure, a vaccination, a dietary change, and chelate therapy. As a major outcome, breath methane mixing ratios show considerable variability within a person-specific range of values. Interestingly, decreased breath methane production often coincided with gastrointestinal complaints whereas influenza infections were mostly accompanied by increased breath methane production. A gastroscopic examination as well as a change to a low-fructose diet led to a dramatic shift of methane mixing ratios from high to low methane production. In contrast, a typhus vaccination as well as single chelate injections resulted in significant short-term methane peaks. Thus, this study clearly shows that humans can change from high to low methane emitters and vice versa within relatively short time periods. In the case of low to medium methane emitters the increase observed in methane mixing ratios, likely resulting from immune reactions and inflammatory processes, might indicate non-microbial methane formation under aerobic conditions. Although detailed reaction pathways are not yet known, aerobic methane formation might be related to cellular oxidative-reductive stress reactions. However, a detailed understanding of the pathways involved in human methane formation is necessary to enable comprehensive interpretation of methane breath levels.
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Affiliation(s)
- Daniela Polag
- Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 236, D-69120 Heidelberg, Germany.
| | - Frank Keppler
- Institute of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 236, D-69120 Heidelberg, Germany
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20
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Mukherjee G, Lee CWZ, Nag SS, Alili A, Cantú Reinhard FG, Kumar D, Sastri CV, de Visser SP. Dramatic rate-enhancement of oxygen atom transfer by an iron(iv)-oxo species by equatorial ligand field perturbations. Dalton Trans 2018; 47:14945-14957. [DOI: 10.1039/c8dt02142b] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The reactivity and characterization of a novel iron(iv)-oxo species is reported that gives enhanced reactivity as a result of second-coordination sphere perturbations of the ligand system.
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Affiliation(s)
- Gourab Mukherjee
- Department of Chemistry
- Indian Institute of Technology Guwahati
- India
| | - Calvin W. Z. Lee
- The Manchester Institute of Biotechnology and the School of Chemical Engineering and Analytical Science
- The University of Manchester
- Manchester M1 7DN
- UK
| | | | - Aligulu Alili
- The Manchester Institute of Biotechnology and the School of Chemical Engineering and Analytical Science
- The University of Manchester
- Manchester M1 7DN
- UK
| | - Fabián G. Cantú Reinhard
- The Manchester Institute of Biotechnology and the School of Chemical Engineering and Analytical Science
- The University of Manchester
- Manchester M1 7DN
- UK
| | - Devesh Kumar
- Department of Applied Physics
- School for Physical Sciences
- Babasaheb Bhimrao Ambedkar University
- Lucknow 226025
- India
| | | | - Sam P. de Visser
- The Manchester Institute of Biotechnology and the School of Chemical Engineering and Analytical Science
- The University of Manchester
- Manchester M1 7DN
- UK
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