sulfurization
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Sulfanová síra je reaktivní, divalentní atom síry vázaný k jiné síře. Modifikuje cysteinové zbytky v řetězcích proteinů a takto mění aktivitu řady enzymů. Je vázána také v molekulách glutathionu a v tomto místě významně zvyšuje antioxidační vlastnosti této sloučeniny. V článku jsou diskutovány analytické možnosti stanovení sulfanové síry a je zmíněna i metoda extraktivní alkylace vyvinutá a využívaná naším pracovištěm. Donorové sloučeniny sulfanové síry jsou kategorizovány do jednotlivých skupin. V článku je diskutováno potenciální využití a efekty tohoto monoelementárního antioxidantu.
Sulfane sulfur is a reactive, divalent sulfur atom bonded to another sulfur. It modifies cysteine residues in proteins and thus changes enzyme activities. Also, it may be bound to glutathione and this greatly increases its antioxidative properties. Analytical methods used for the determination of sulfane sulfur are discussed and our developed method using an extractive alkylation technique is mentioned. The sulfane sulfur donor compounds are described and categorized. The potential use and future perspectives of this monoelemental antioxidant are summarised and discussed.
- Klíčová slova
- sulfanová síra, donory sulfanové síry,
- MeSH
- antioxidancia MeSH
- lidé MeSH
- síra * analýza metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
The sulfurization efficiency of 25 3-substituted-1,2,4-dithiazole-5-ones and 5-thiones towards triphenyl phosphite in acetonitrile, DCM, THF and toluene at 25 °C was evaluated. All the 1,2,4-dithiazoles are much better sulfurizing reagents than commercially available agents (PADS, TETD, Beaucage's reagent). The most efficient sulfurizing agents in all solvents are 3-phenoxy (4), 3-phenylthio (5) and 3-ethoxy-1,2,4-dithiazole-5-one (1) whose reactivity is at least two orders of magnitude higher than that of other 1,2,4-dithiazoles. Contrary to a previous report, the sulfurization with 1 does not yield carbonylsulfide and ethyl cyanate as the additional reaction products but unstable ethoxythiocarbonyl isocyanate which has been trapped with 4-methoxyaniline. Similar trapping experiments have proven that the site of attack is at the sulfur adjacent to the C=O group for compounds 4 and 5. The reaction pathway involves rate-limiting initial nucleophilic attack of the phosphorus at sulfur followed by decomposition of the phosphonium intermediate to the corresponding phosphorothioate and isocyanate/isothiocyanate species. The existence of the phosphonium intermediate during sulfurization of triphenyl phosphine with 3-phenyl-1,2,4-dithiazole-5-thione (7a) was proven using kinetic studies. From the Hammett and Brønsted correlations and from other kinetic measurements it was concluded that the transition-state structure is almost apolar for the most reactive 1,2,4-dithiazoles whereas a polar structure resembling a zwitter-ionic intermediate may be more appropriate for the least reactive 1,2,4-dithiazoles. The extent of P–S bond formation and S–S bond cleavage is very similar in all reaction series but it gradually decreases with the reactivity of the 1,2,4-dithiazole derivatives.
Sulfur-oxidizing bacteria (SOB) are versatile microorganisms known for their ability to oxidize various reduced sulfur compounds, namely, elemental sulfur (S0), hydrogen sulfide (H2S), tetrathionate (S4O62-), and trithionate (S3O62-) to sulfate (SO42-). In this study, out of twelve SOB isolates from rice rhizosphere, five were screened based on their sulfur oxidation potential, viz., SOB1, SOB2, SOB3, SOB4, and SOB5, and were identified as Ochrobactrum soli SOB1, Achromobacter xylosoxidans SOB2, Stenotrophomonas maltophilia SOB3, Brucella tritici SOB4, and Stenotrophomonas pavanii SOB5, respectively. All the isolates displayed chemolithotrophic nutritional mode by consuming thiosulfate and accumulating trithionate and tetrathionate in the growth medium which is ultimately oxidized to sulfate. The strains were authenticated with the production of thiosulfate oxidizing enzymes such as rhodanese and sulfite oxidase. Despite their tendency to oxidize reduced sulfur compounds, B. tritici SOB4 and S. pavanii SOB5 were also found to possess phosphate and zinc solubilization potential, acetic acid, and indole acetic acid (IAA) production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity. The presence of sulfanyl (R-SH) groups was noticed in the A. xylosoxidans SOB2. Elemental sulfur conversion into sulfate was noted in the S. maltophilia SOB3, and hydrogen sulfide conversion into sulfate was observed in the Ochromobacter soli SOB1. Sulfur oxidation potential coupled with beneficial properties of the isolates widen the knowledge on SOB.
We explored the use of Raman spectroscopy to simultaneously monitor the presence of different biomarkers (carotenoids, elemental sulfur) within single cells of the purple sulfur photosynthetic bacteria Allochromatium vinosum and A. warmingii. Raman microspectrometry using excitation at 532 nm allowed the detection of different carotenoids. Raman signals of elemental sulfur appeared soon after feeding starved cells with sulfide. Raman spectroscopy is thus a convenient and sensitive technique to qualitatively and semiquantitatively assess the presence of different compounds of interest within single bacterial cells.
Hydrogen sulfide is widely known as the most undesirable component of biogas that caused not only serious sensoric and toxic problems, but also corrosion of concrete and steel structures. Many agricultural and industrial waste used in biogas production, may contain a large amount of substances that serve as direct precursors to the formation of sulfide sulfur-sources of hydrogen sulfide in the biogas. Biological desulfurization methods are currently promoted to abiotic methods because they are less expensive and do not produce undesirable materials which must be disposed of. The final products of oxidation of sulfides are no longer hazardous. Biological removal of sulfide from a liquid or gaseous phase is based on the activity of sulfur-oxidizing bacteria. They need an oxidizing agent such as an acceptor of electrons released during the oxidation of sulfides-atmospheric oxygen or oxidized forms of nitrogen. Different genera of sulfur-oxidizing bacteria and their technological application are discussed.
In winegrowing, sulfur compounds are as important as sugars, acids or amino nitrogen. They are present in every living organism serving for building-up of tissues and control functions. Without utilizable sulfur and some of its active compounds it would not be possible to raise grapes, ferment grape juice and produce wine. Concentrations of sulfur in musts are not sufficient for creation of perfect aroma of wine. The metabolisms of sugars, nitrogen and sulfur compounds in yeasts are closely linked. Production of perfect, healthy wine is influenced by the composition of must, presence of all nutritional components and by the strain of wine yeasts as well.
High soil pH and excess CaCO3 are major contributors to calcareous soil limitations on crops' access to essential nutrients, especially phosphorus (P) and micronutrients, which in turn impact pulses yields and growth. The purpose of this study was to determine the effect of bio sulfur granules (BSG) on the growth of black gram and the availability of nutrients in calcareous vertisols deficient in sulfur. BSG was developed by using sulfur-oxidizing bacteria (SOB) and elemental sulfur (ES) through an incubation study. Developed BSG was tested in a pot and field conditions to evaluate their effectiveness on black gram growth and yield. In the incubation study, soil treated with Methylobacterium thiocyanatum VRI7-A4 and ES (40 kg S/ha) significantly decreased pH and increased available S (SO42-) in calcareous soils. After 40 days of incubation, the solubility of P, Fe, and Zn was greatly increased by the addition of ES @ 40 kg S/ ha in combination with M. thiocyanatum VRI7-A4 or Pandoraea thiooxydans ATSB16. Black gram in S-deficient calcareous soil was improved by the application of BSG (ES @ 40 kg S/ ha with M. thiocyanatum VRI7-A7) in terms of root and shoot lengths, nodule number, plant biomass, pod yield, and biological yield as compared to control. The same treatment greatly increased plant nutrient intake as well as the concentrations of P, Fe, and Zn in the soil. The results showed that the addition of BSG granules (ES @ 40 kg S/ha + M. thiocyanatum VRI7-A4) to calcareous vertisol deficient in S enhanced the nutrient solubility through S oxidation. The developed bio sulfur granules may be added to the fertilizer schedule of the pulses growers to get improved crop growth and yield of black gram in calcareous soil.
Práce shrnuje nové experimentální poznatky týkající se jednotlivých skupin organických sirnýchlátek česneku: sulfoxidů, thiosulfinátů, ajoenů, vinyldithiinů, alkyl a alkensulfidů a glutamylpep-tidů sirných aminokyselin, jejich transformačních reakcí (daných teplotou, pH, extrakčním prostře-dím a časem) a výsledných produktů transformací (obr. 1 a 2). Zabývá se aktivitou enzymu alliinázynezbytné pro přeměnu sulfoxidů přítomných v celistvém česneku, její izolací a stabilitou, jakoži stabilitou dominantního thiosulfinátu allicinu v různých prostředích a simulovaných tělních teku-tinách. Poukazuje na studie metabolizmu a přeměn nejdůležitějších sirných komponent in vitro nahepatocytech a na izolovaných játrech potkanů a in vivo na potkanech včetně skladby vydechova -ného vzduchu. Z publikovaných prací vyplývá, že všechny rozdílné degradační produkty thiosulfi-nátů, hlavně převažujícího allicinu, jsou nositeli rozmanitých biologických aktivit. Práce rovněžuvádí typy komerčních preparátů připravovaných z česneku, jejich rozdílnosti a značnou variabilituv obsahu účinných látek.
The paper sums up new experimental knowledge concerning the individual groups of organicsulfurous substances of the garlic: sulfoxides, thiosulfinates, ajoens, vinyldithiines, alkyl and alkenesulfides and glutamylpeptides of sulfurous amino acids, their transformation reactions (based onthe temperature, pH, extraction medium, and time) and the final products of transformations(Scheme 1, 2). It deals with the activity of the enzyme alliinase necessary for the transformation ofsulfoxides present in the whole garlic, its isolation and stability as well as the stability of thedominant thiosulfinate allicin in various media and simulated body fluids. It refers to the studiesof the metabolism and transformations of the most important sulfurous components performed invitro on the hepatocytes and on the isolated rat liver, and those carried out in vivo on the rats andincluding the examination of the composition of the exhaled air. It follows from published papersthat all different degradation products of thiosulfinates, mainly the prevailing allicin, are carriersof various biological activities. The paper also lists the types of commercial preparations preparedfrom the garlic, their differences, and considerable variability of their contents of active principles.
Iron-sulfur (Fe-S) clusters are essential cofactors that enable proteins to transport electrons, sense signals, or catalyze chemical reactions. The maturation of dozens of Fe-S proteins in various compartments of every eukaryotic cell is driven by several assembly pathways. The ubiquitous cytosolic Fe-S cluster assembly (CIA) pathway, typically composed of eight highly conserved proteins, depends on mitochondrial Fe-S cluster assembly (ISC) machinery. Giardia intestinalis contains one of the smallest eukaryotic genomes and the mitosome, an extremely reduced mitochondrion. Because the only pathway known to be retained within this organelle is the synthesis of Fe-S clusters mediated by ISC machinery, a likely function of the mitosome is to cooperate with the CIA pathway. We investigated the cellular localization of CIA components in G. intestinalis and the origin and distribution of CIA-related components and Tah18-like proteins in other Metamonada. We show that orthologs of Tah18 and Dre2 are missing in these eukaryotes. In Giardia, all CIA components are exclusively cytosolic, with the important exception of Cia2 and two Nbp35 paralogs, which are present in the mitosomes. We propose that the dual localization of Cia2 and Nbp35 proteins in Giardia might represent a novel connection between the ISC and the CIA pathways.
- MeSH
- cytoplazma MeSH
- cytosol metabolismus MeSH
- Giardia lamblia genetika metabolismus MeSH
- mitochondriální proteiny metabolismus MeSH
- mitochondrie metabolismus MeSH
- proteiny obsahující železo a síru metabolismus MeSH
- síra metabolismus MeSH
- železo metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
The conventional stoichiometry of the oxidation of elemental sulfur by ferric iron in Acidithiobacillus ferrooxidans was not in agreement with our experimental data in terms of ferrous iron and proton formation. Reaction modelling under the actual conditions of bacterial activity resulted in a different stoichiometry, where additional iron species participate in the process to affect the number of released protons. The suggested reaction equation may more accurately predict the intensity of environmental acidification during the anaerobic bioprocess.
- MeSH
- Acidithiobacillus metabolismus MeSH
- anaerobióza MeSH
- energetický metabolismus MeSH
- oxidace-redukce MeSH
- síra metabolismus MeSH
- železité sloučeniny metabolismus MeSH
- železnaté sloučeniny metabolismus MeSH
- železo metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
