Oxidation of sulfide to sulfate is known to consist of several steps. Key intermediates in this process are the so-called small oxoacids of sulfur (SOS)-sulfenic HSOH (hydrogen thioperoxide, oxadisulfane, or sulfur hydride hydroxide) and sulfoxylic S(OH) acids. Sulfur monoxide can be considered as a dehydrated form of sulfoxylic acid. Although all of these species play an important role in atmospheric chemistry and in organic synthesis, and are also invoked in biochemical processes, they are quite unstable compounds so much so that their physical and chemical properties are still subject to intense studies. It is well-established that sulfoxylic acid has very strong reducing properties, while sulfenic acid is capable of both oxidizing and reducing various substrates. Here, in this review, the mechanisms of sulfide oxidation as well as data on the structure and reactivity of small sulfur-containing oxoacids, sulfur monoxide, and its precursors are discussed.
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http://dx.doi.org/10.3390/molecules24152768 | DOI Listing |
Nature
December 2024
Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, Helsinki, Finland.
Aircraft observations have revealed ubiquitous new particle formation in the tropical upper troposphere over the Amazon and the Atlantic and Pacific oceans. Although the vapours involved remain unknown, recent satellite observations have revealed surprisingly high night-time isoprene mixing ratios of up to 1 part per billion by volume (ppbv) in the tropical upper troposphere. Here, in experiments performed with the CERN CLOUD (Cosmics Leaving Outdoor Droplets) chamber, we report new particle formation initiated by the reaction of hydroxyl radicals with isoprene at upper-tropospheric temperatures of -30 °C and -50 °C.
View Article and Find Full Text PDFChimia (Aarau)
November 2024
Center for Energy and Environment, Paul Scherrer Institute, Villigen, CH-5232 Villigen, Switzerland.
Methods Enzymol
November 2024
Department of Chemistry, Boston University, Cummington Mall, Boston, MA, United States. Electronic address:
The oxo-acid:ferredoxin oxidoreductase (OFOR) superfamily of enzymes are responsible for the reversible interconversion of CO and oxo-acids, using CoA-derivatives as co-substrates, and requiring redox equivalents in the form of a soluble redox-carrier protein ferredoxin (Fd). Ultimately, these enzymes are responsible for the reduction of CO to form pyruvate (in the case of PFOR) and oxo-glutarate (in the case of OGOR), by the reductive carboxylation reaction of acetyl-CoA and succinyl-CoA, respectively. The nature and kind of Fd that is the best redox-carrier to support the reductive reaction has been poorly studied to date.
View Article and Find Full Text PDFStructure
November 2024
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Biophysics and Quantitative Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, United States. Electronic address:
Enzymes of the 2-oxoacid:ferredoxin oxidoreductase (OFOR) superfamily catalyze the reversible oxidation of 2-oxoacids to acyl-coenzyme A esters and carbon dioxide (CO)using ferredoxin or flavodoxin as the redox partner. Although members of the family share primary sequence identity, a variety of domain and subunit arrangements are known. Here, we characterize the structure of a four-subunit family member: the pyruvate:ferredoxin oxidoreductase (PFOR) from the methane producing archaeon Methanosarcina acetivorans (MaPFOR).
View Article and Find Full Text PDFCrit Rev Toxicol
September 2024
Department of Toxicology, University of Würzburg, Würzburg, Germany.
The term "glycation compounds" comprises a wide range of structurally diverse compounds that are formed endogenously and in food the Maillard reaction, a chemical reaction between reducing sugars and amino acids. Glycation compounds produced endogenously are considered to contribute to a range of diseases. This has led to the hypothesis that glycation compounds present in food may also cause adverse effects and thus pose a nutritional risk to human health.
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