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Sulfur Source (sulfur + source)
Selected AbstractsSite-directed mutagenesis of the active site loop of the rhodanese-like domain of the human molybdopterin synthase sulfurase MOCS3FEBS JOURNAL, Issue 11 2007Major differences in substrate specificity between eukaryotic, bacterial homologs Sequence alignments of human molybdopterin synthase sulfurase, MOCS3, showed that the N-terminal domain is homologous to Escherichia coli MoeB, whereas the C-terminal domain is homologous to rhodanese-like proteins. Previous studies showed that the activity of the separately purified rhodanese-like domain of MOCS3 displayed 1000-fold lower activity in comparison to bovine rhodanese with thiosulfate as sulfur source. When the six amino acid active site loop of MOCS3 rhodanese-like domain was exchanged with the loop found in bovine rhodanese, thiosulfate:cyanide sulfurtransferase activity was increased 165-fold. Site-directed mutagenesis of each individual residue of the active site loop of the MOCS3 rhodanese-like domain showed that the charge of the last amino acid determines thiosulfate sulfurtransferase activity. Replacing Asp417 by threonine resulted in 90-fold increased activity, whereas replacing it by arginine increased the activity 470-fold. Using a fully defined in vitro system containing precursor Z, MOCS2A, E. coli MoaE, E. coli MoeB, Mg-ATP, MOCS3 rhodanese-like domain, and thiosulfate, it was shown that sulfur transfer to MOCS2A was also affected by the alterations, but not as drastically. Our studies revealed that in humans and most eukaryotes thiosulfate is not the physiologic sulfur donor for MOCS3, whereas in bacterial homologs, which have an arginine at the last position of the active site loop, thiosulfate can be used as a sulfur source for molybdenum cofactor biosynthesis. The phylogenetic analysis of MoeB homologs showed that eukaryotic homologs are of bacterial origin. Furthermore, it could be shown that an MoeB homolog named MoeZ, where the dual CXXC zinc-binding motif of the MoeB domain is not present, arose independently several times during evolution. [source] Preparation-Condition Dependence of Hybrid SiO2 -Coated CdTe Nanocrystals with Intense and Tunable PhotoluminescenceADVANCED FUNCTIONAL MATERIALS, Issue 8 2010Ping Yang Abstract When aqueously prepared CdTe nanocrystals (NCs) are coated with a SiO2 shell containing Cd ions and a sulfur source, they show a drastic increase in photoluminescence (PL) efficiency with a significant red shift and spectral narrowing after reflux. This is ascribed to the creation of a hybrid structure characterized by the formation of CdS-like clusters in the vicinity of the NCs in the SiO2 shell. Since these clusters are close to the NCs, their effective size increases to reduce the quantum size effect. The dependences of the PL properties on the preparation conditions are systematically investigated. The PL efficiency increases from 28% to 80% in the best case with a red shift of 80,nm. The PL behaviors differ from those of normal CdTe NCs and include less temperature quenching and longer PL lifetime. The SiO2 coating enables bioconjugation with IgG without deterioration of PL efficiency, making hybrid NCs amenable for bioapplication. [source] Arylsulfonates as sole source of sulfur for Clostridium pasteurianum DSM 12136JOURNAL OF BASIC MICROBIOLOGY, Issue 4 2005Chih-Ching Chien Prof. A variety of arylsulfonates were examined for their ability to support growth of Clostridium pasteurianum as sole source of sulfur. Among the eleven different arylsulfonates tested, six of them (benzenesulfonate, 4-toluenesulfonate, 4-xylene-2-sulfonate, 4-aminobenzenesulfonate, 4-sulfobenzoic acid, 1,3-benzenedisulfonate) could serve as sole sulfur source for C. pasteurianum DSM 12136. None of the sulfonates tested could serve as sole sulfur source for C. pasteurianum ATCC 6013. The two C. pasteurianum in this study could not utilize any of these sulfonates as sole carbon and energy source. We demonstrated that desulfonation of arylsulfonates could take place under anoxic conditions and the sulfur atom of these compounds could be utilized as sole source of sulfur by anaerobic bacteria. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Interaction between metabolism of atmospheric H2S in the shoot and sulfate uptake by the roots of curly kale (Brassica oleracea)PHYSIOLOGIA PLANTARUM, Issue 4 2000Sue Westerman Exposure of curly kale (Brassica oleracea L.) to gaseous H2S resulted in a decreased sulfate uptake by the roots. At 0.2 ,l l,1 H2S, a level sufficient to meet the sulfur need of plants for growth, the sulfate uptake was maximally decreased by 50% after 3 or 4 days of exposure. Higher levels up to 0.8 ,l l,1 H2S did not further affect the sulfate uptake. The nitrate uptake was not affected upon exposure to 0.2,0.8 ,l l,1 H2S. H2S exposure did not affect the sulfate content of the plants, but it resulted in an increased content of thiols and cysteine in the shoots, whereas that in the roots was hardly affected. Plants grown under sulfate-deprived conditions had a decreased biomass production, very low content of sulfate and decreased content of thiols in both shoot and roots. Sulfate-deprived plants had a two-fold higher sulfate uptake after transfer to a sulfate-containing solution, while nitrate uptake was decreased by 50%. When sulfate-deprived plants were exposed to 0.25 ,l l,1 H2S, plant biomass production and nitrate uptake were restored but the sulfate uptake after transfer to a sulfate-containing solution remained high. Also here, H2S exposure resulted in an increase in the thiol and cysteine content of both shoot and roots, whereas the content of sulfate remained low. The presented results clearly demonstrate a direct interaction between the regulation of sulfate uptake by the roots and the metabolism of gaseous H2S by the shoot. Curly kale is able to use both sulfate and H2S as a sulfur source for growth, and matching the supply of sulfur in the form of pedospheric or atmospheric sulfur to the sulfur needed for growth appears to be regulated nicely. However, the significance of thiols as signal in the shoot/root coordination of sulfate uptake appears to be limited. From the data it is evident that there is no direct mutual regulation between the uptake of sulfate and nitrate by the roots. [source] Biological Conversion of Anglesite (PbSO4) and Lead Waste from Spent Car Batteries to Galena (PbS)BIOTECHNOLOGY PROGRESS, Issue 4 2002Jan Weijma Lead paste, a solid mixture containing PbSO4, PbO2, PbO/Pb(OH)2precipitate, and elemental Pb, is one of the main waste fractions from spent car batteries. Biological sulfidation represents a new process for recovery of lead from this waste. In this process the lead salts in lead paste are converted to galena (PbS) by sulfate-reducing bacteria. This paper investigates a continuous process for sulfidation of anglesite (PbSO4), the main constituent of lead paste, and lead paste, consisting of a laboratory-scale gas-lift bioreactor to which a slurry of anglesite or lead paste was supplied. Sulfate or elemental sulfur was added as an additional sulfur source. Hydrogen gas served as an electron donor for the biological reduction of sulfate and elemental sulfur to sulfide by sulfate- and sulfur-reducing bacteria. Anglesite was almost completely converted to galena at a loading rate of 19 kg of PbSO4m,3day,1, producing a sludge of which the crystalline lead phases consisted of >98% PbS (galena) and 1,2% elemental Pb. With lead paste, stable sulfidation rates of up to 17 kg of lead paste m,3day,1were demonstrated, producing a sludge of which the crystalline lead phases consisted of an estimated >96% PbS, 1,2% elemental Pb, and 1,2% PbO2. [source] Production of a Desulfurization Biocatalyst by Two-Stage Fermentation and Its Application for the Treatment of Model and Diesel OilsBIOTECHNOLOGY PROGRESS, Issue 5 2001Je Hwan Chang For the production of oil-desulfurizing biocatalyst, a two-stage fermentation strategy was adopted, in which the cell growth stage and desulfurization activity induction stage were separated. Sucrose was found to be the optimal carbon source for the growth of GordonianitidaCYKS1. Magnesium sulfate was selected to be the sulfur source in the cell growth stage. The optimal ranges of sucrose and magnesium sulfate were 10,50 and 1,2.5 g L,1, respectively. Such a broad optimal concentration of sucrose made the fed-batch culture easy, while the sucrose concentration was maintained between 10,20 g L,1 in the actual operation. As a result, 92.6 g L,1 of cell mass was acquired by 120 h of fed-batch culture. This cell mass was over three times higher than a previously reported result, though the strain used was different. The desulfurization activity of the harvested cells from the first stage culture was induced by batch cultivation with dibenzothiophene as the sole sulfur source. The optimal induction time was found to be about 4 h. The resting-cell biocatalyst made from the induced cells was applied for the deep desulfurization of a diesel oil. It was observed that the sulfur content of the diesel oil decreased from 250 mg-sulfur L-oil,1 to as low as 61 mg-sulfur L-oil,1 in 20 h. It implied that the biocatalyst developed in this study had a good potential to be applied to a deep desulfurization process to produce ultra-low-sulfur fuel oils. [source] Pathways and Substrate Specificity of DMSP Catabolism in Marine Bacteria of the Roseobacter CladeCHEMBIOCHEM, Issue 3 2010Jeroen S. Dickschat Dr. Abstract The volatiles released by Phaeobacter gallaeciensis, Oceanibulbus indolifex and Dinoroseobacter shibae have been investigated by GC-MS, and several MeSH-derived sulfur volatiles have been identified. An important sulfur source in the oceans is the algal metabolite dimethylsulfoniopropionate (DMSP). Labelled [2H6]DMSP was fed to the bacteria to investigate the production of volatiles from this compound through the lysis pathway to [2H6]dimethylsulfide or the demethylation pathway to [2H3]-3-(methylmercapto)propionic acid and lysis to [2H3]MeSH. [2H6]DMSP was efficiently converted to [2H3]MeSH by all three species. Several DMSP derivatives were synthesised and used in feeding experiments. Strong dealkylation activity was observed for the methylated ethyl methyl sulfoniopropionate and dimethylseleniopropionate, as indicated by the formation of EtSH- and MeSeH-derived volatiles, whereas no volatiles were formed from dimethyltelluriopropionate. In contrast, the dealkylation activity for diethylsulfoniopropionate was strongly reduced, resulting in only small amounts of EtSH-derived volatiles accompanied by diethyl sulfide in P. gallaeciensis and O. indolifex, while D. shibae produced the related oxidation product diethyl sulfone. The formation of diethyl sulfide and diethyl sulfone requires the lysis pathway, which is not active for [2H6]DMSP. These observations can be explained by a shifted distribution between the two competing pathways due to a blocked dealkylation of ethylated substrates. [source] Sulfur-Selective Desulfurization of Dibenzothiophene and Diesel Oil by Newly Isolated RhodococcuserythropolisNCC-1CHINESE JOURNAL OF CHEMISTRY, Issue 3 2007Yu-Guang Li Abstract A dibenzothiophene (DBT)-desulfurizing bacteria strain was isolated from oil-contaminated soils and identified as Rhodococcuserythropolis NCC-1. Strain NCC-1 was found to convert DBT to hydroxybiphenyl (2-HBP) via the 4S pathway and also be able to use organic sulfur compounds other than DBT as a sole sulfur source. The strain could desulfurize 4,6-dimethyldibenzothiophene (4,6-DMDBT), which is one of the most recalcitrant dibenzothiophene derivatives to hydrodesulfurization. When two type of oils, a model oil [n -hexadecane (n -C16) containing DBT] and a hydrodesulfurized diesel oil with various organic sulfur compounds, were treated with Rhodococcuserythropolis NCC-1 cells, the total sulfur content significantly decreased, from 150 to 20 mg/L for n -C16 and from 554 to 274 mg/L for diesel oil. The newly isolated strain NCC-1 is considered to have good potential for application in the biodesulfurization of fossil fuels. [source] Riding the sulfur cycle , metabolism of sulfonates and sulfate esters in Gram-negative bacteriaFEMS MICROBIOLOGY REVIEWS, Issue 2 2000Michael A. Kertesz Abstract Sulfonates and sulfate esters are widespread in nature, and make up over 95% of the sulfur content of most aerobic soils. Many microorganisms can use sulfonates and sulfate esters as a source of sulfur for growth, even when they are unable to metabolize the carbon skeleton of the compounds. In these organisms, expression of sulfatases and sulfonatases is repressed in the presence of sulfate, in a process mediated by the LysR-type regulator protein CysB, and the corresponding genes therefore constitute an extension of the cys regulon. Additional regulator proteins required for sulfonate desulfonation have been identified in Escherichia coli (the Cbl protein) and Pseudomonas putida (the AsfR protein). Desulfonation of aromatic and aliphatic sulfonates as sulfur sources by aerobic bacteria is oxygen-dependent, carried out by the ,-ketoglutarate-dependent taurine dioxygenase, or by one of several FMNH2 -dependent monooxygenases. Desulfurization of condensed thiophenes is also FMNH2 -dependent, both in the rhodococci and in two Gram-negative species. Bacterial utilization of aromatic sulfate esters is catalyzed by arylsulfatases, most of which are related to human lysosomal sulfatases and contain an active-site formylglycine group that is generated post-translationally. Sulfate-regulated alkylsulfatases, by contrast, are less well characterized. Our increasing knowledge of the sulfur-regulated metabolism of organosulfur compounds suggests applications in practical fields such as biodesulfurization, bioremediation, and optimization of crop sulfur nutrition. [source] Fascinating organosulfur functionalities: Polychalcogens as diatomic sulfur sourcesHETEROATOM CHEMISTRY, Issue 5 2007Eli Zysman-Colman Recent work on the chemistry of dialkoxy disulfides is summarized. It includes various aspects of their structure and relationship to the isomeric thionosulfites as well as their use as diatomic sulfur precursors. © 2007 Wiley Periodicals, Inc. 18:449,459, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20341 [source] Simultaneous expression and maturation of the iron-sulfur protein ferredoxin in a cell-free systemBIOTECHNOLOGY & BIOENGINEERING, Issue 1 2006Marcus E. Boyer Abstract The model iron-sulfur (Fe-S) protein ferredoxin (Fd) from Synechocystis sp. PCC 6803 has been simultaneously produced and matured in a cell-free production system. After 6 h of incubation at 37°C, Fd accumulated to >450 µg/mL. Essentially all was soluble, and 85% was active. Production and maturation of the protein in the cell-free system were found to be dependent in a coupled manner on the concentration of the supplemented iron and sulfur sources, ferrous ammonium sulfate and cysteine, respectively. The recombinant expression of ISC helper proteins during cell extract preparation did not increase cell-free Fd accumulation or activity, although the efficiency of iron and cysteine utilization increased. Fd maturation was independent of protein production rate, and proceeded at a constant rate throughout the period of active translation. In addition, incubation of denatured apo Fd with cell-free reaction components resulted in recovery of Fd activity, supporting the interpretation that maturation mechanisms did not act co-translationally. Incubation at 28°C increased total and active protein accumulation, but decreased the ratio of active to total Fd produced. In summary, the high product yields and folding efficiency make the cell-free system described here an attractive platform for the study of Fe-S protein production and maturation. The system enables both small-volume, high throughput investigations as well as larger scale production. To our knowledge, this is the first demonstration of directed, high-yield production and maturation of an Fe-S protein in a cell-free system. © 2006 Wiley Periodicals, Inc. [source] | |||||||||||||