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PubMed2005

New structural features in triphenylphosphinesilver(I) sulfanylcarboxylates.

We investigated the reactions of 1.5 : 1 : 1 mole ratio mixtures of triphenylphosphine, silver nitrate and 3-(aryl)-2-sulfanylpropenoic acids H(2)xspa in chloroform/water, where in the acid nomenclature, spa = 2-sulfanylpropenoato and x = p, Clp, mp, diBr-o-hp or f with p = 3-phenyl-, Clp = 3-(2-chlorophenyl)-, mp = 3-methoxyphenyl-, diBr-o-hp = 3-(3,5-dibromo-2-hydroxyphenyl)- and f = 3-(2-furyl)-. The compounds [Ag(PPh(3))(Hpspa)](1), [(AgPPh3)2(xspa)][x = Clp (2), o-mp (3), p-mp (4), diBr-o-hp (5) and f (6)] and [Ag(PPh3)3(Hfspa)](7) were isolated and all except 7 were characterized by IR, Raman and FAB mass spectrometry and by 1H, 13C and 31P NMR spectroscopy. Compound 6 was also characterized by (13)C CP/MAS, and compounds 1 and 6 by (109)Ag NMR spectroscopy. The crystal structures of 1, 2, 3, 4.(CH3)2CO, 5, 6.(CH3)2CO and 7 were determined by X-ray diffraction. has a supramolecular structure based on hydrogen bonding between dinuclear units, and all the other complexes adopt discrete structures. 2, 3, 4.(CH3)2CO, 5, and 6.(CH3)2CO are tetranuclear, and 7 mononuclear. The tetranuclear complexes contain the eight-membered coordination ring Ag4S2O2 (2, 3, 4.(CH3)2CO, 6.(CH3)2CO) or the twelve-membered ring Ag4(CO2)2S2 (5).

Hydrogen Bonding↗
PubMed2005

Synthetic strategies to chiral organosulfur donors related to bis(ethylenedithio)tetrathiafulvalene.

Syntheses of enantiopure organosulfur donors by three different strategies requiring only four-six steps are reported. The key step involves either double substitution of an enantiopure cyclic sulfate ester by a dithiolate, attachment of a chiral diol as a ketal, or completely diastereoselective cycloaddition of 1,3-dithiole-2,4,5-trithione to an enantiopure alkene.

Magnetic Resonance Spectroscopy↗
PubMed2003

Relationship between tongue coating and secretory-immunoglobulin A level in saliva obtained from patients complaining of oral malodor.

AIM: The aim of this study was to confirm the relationships between oral malodor and periodontal condition, oral malodor and tongue coating, and to investigate the secretory-immunoglobulin A (S-IgA) level in saliva in relation to the accumulation of tongue coating. METHODS: Fifty-four patients complaining of oral malodor were included in the study. Their periodontal conditions, tongue coating status and salivary characteristics (flow rate, protein and S-IgA concentrations) were assessed in addition to the level of volatile sulfur compounds (VSC) in oral cavity. The patients were divided into three groups according to their tongue coating level. RESULTS: There are significant relationships between oral malodor and specific periodontal parameters used. The degree of tongue coating was also significantly correlated with the amount of H2S, CH3SH and the total amount of VSC determined. The concentration of S-IgA in the group identified as slight tongue coating was significantly higher than in the moderate or the severe group. By Western immunoblotting analysis, a high level of S-IgA specific to Streptococcus species was recognized in all groups, whereas the reactivity of Porphyromonas gingivalis and Fusobacterium nucleatum with S-IgA was very weak in both the slight and the moderate groups. CONCLUSION: Data herein indicate that tongue coating is closely related to oral malodor. Furthermore, S-IgA in saliva may influence the accumulation of tongue coating, and S-IgA antibodies directed to Streptococcus species may play a role in protective immunity against the initial colonization of tongue plaque.

Adolescent↗
PubMed2004

Localization, purification and properties of a tetrathionate hydrolase from Acidithiobacillus caldus.

The moderately thermophilic bacterium Acidithiobacillus caldus is found in bacterial populations in many bioleaching operations throughout the world. This bacterium oxidizes elemental sulfur and other reduced inorganic sulfur compounds as the sole source of energy. The purpose of this study was to purify and characterize the tetrathionate hydrolase of A. caldus. The enzyme was purified 16.7-fold by one step chromatography using a SP Sepharose column. The purified enzyme resolved into a single band in 10% polyacrylamide gel, both under denaturing and native conditions. Its homogeneity was confirmed by N-terminal amino acid sequencing. Tetrathionate hydrolase was shown to be a homodimer with a molecular mass of 103 kDa (composed from two 52 kDa monomers). The purified enzyme had optimum activity at pH 3.0 and 40 degrees C and an isoelectric point of 9.8. The periplasmic localization of the enzyme was determined by differential fractionation of A. caldus cells. Detected products of the tetrathionate hydrolase reaction were thiosulfate and pentathionate as confirmed by RP-HPLC analysis. The activity of the purified enzyme was drastically enhanced by divalent metal ions.

Acidithiobacillus↗
PubMed2002

Molluscum contagiosum: a case series.

Molluscum contagiosum is a benign and contagious disease of the skin. In a series of 30 consecutive patients, 15 had full resolution, 12 were improved. Brief case histories of the 15 patients who fully resolved are presented. The homeopathic medicines most frequently associated with positive outcome were Natrum sulphuricum, Sulphur and Natrum muriaticum.

Adolescent↗
PubMed2006

The leaf volatile constituents of Isatis tinctoria by Solid-Phase Microextraction and Gas chromatography/Mass Spectrometry.

The leaf volatile constituents of Isatis tinctoria L. (Brassicaceae) have been studied by Solid-Phase Microextraction and Gas chromatography/Mass Spectrometry (SPME/GC-MS). Seventy components were fully characterized by mass spectra, linear retention indices, and injection of standards; the average composition (ppm) as single components and classes of substances is reported. Aliphatic hydrocarbons, acids, alcohols, aldehydes and esters, aromatic aldehydes, esters and ethers, furans, isothiocyanates and thiocyanates, sulfurated compounds, nitriles, terpenes and sesquiterpenes were identified. Leaf volatiles in Isatis tinctoria L. were characterized by a high amount of isothiocyanates which accounted for about 40 % of the total volatile fraction. Isothiocyanates are important and characteristic flavour compounds in Brassica vegetables and the cancer chemo-protective attributes are recently responsible for their growing interest.

Gas Chromatography-Mass Spectrometry↗
PubMed2003

Retrofitting existing chemical scrubbers to biotrickling filters for H2S emission control.

Biological treatment is a promising alternative to conventional air-pollution control methods, but thus far biotreatment processes for odor control have always required much larger reactor volumes than chemical scrubbers. We converted an existing full-scale chemical scrubber to a biological trickling filter and showed that effective treatment of hydrogen sulfide (H2S) in the converted scrubber was possible even at gas contact times as low as 1.6 s. That is 8-20 times shorter than previous biotrickling filtration reports and comparable to usual contact times in chemical scrubbers. Significant removal of reduced sulfur compounds, ammonia, and volatile organic compounds present in traces in the air was also observed. Continuous operation for >8 months showed stable performance and robust behavior for H2S treatment, with pollutant-removal performance comparable to that achieved by using a chemical scrubber. Our study demonstrates that biotrickling filters can replace chemical scrubbers and be a safer, more economical technique for odor control.

Air Pollution↗
PubMed2003

The genome sequence of Blochmannia floridanus: comparative analysis of reduced genomes.

Bacterial symbioses are widespread among insects, probably being one of the key factors of their evolutionary success. We present the complete genome sequence of Blochmannia floridanus, the primary endosymbiont of carpenter ants. Although these ants feed on a complex diet, this symbiosis very likely has a nutritional basis: Blochmannia is able to supply nitrogen and sulfur compounds to the host while it takes advantage of the host metabolic machinery. Remarkably, these bacteria lack all known genes involved in replication initiation (dnaA, priA, and recA). The phylogenetic analysis of a set of conserved protein-coding genes shows that Bl. floridanus is phylogenetically related to Buchnera aphidicola and Wigglesworthia glossinidia, the other endosymbiotic bacteria whose complete genomes have been sequenced so far. Comparative analysis of the five known genomes from insect endosymbiotic bacteria reveals they share only 313 genes, a number that may be close to the minimum gene set necessary to sustain endosymbiotic life.

Animals↗
PubMed1977

Derepression of ATP sulfurylase by the sulfate analogs molybdate and selenate in cultured tobacco cells.

Molybdate and selenate are structural analogs of sulfate that inhibit synthesis of adenosine 5'-phosphosulfate by ATP sulfurylase (sulfate adenylyltransferase, ATP:sulfate adenylyltransferase, EC 2.7.7.4) in crude extracts of tobacco XD cells. Both of these anions derepress ATP sulfurylase in cells growing on sulfate, but not in cells growing on L-cysteine. However, the two anions appear to derepress by different mechanisms. Molybdate caused derepression only at concentrations that were in excess over sulfate and were sufficient to inhibit growth and protein accumulation, indicating that the derepression resulted from sulfur starvation. Selenate caused derepression at one-tenth the concentration of sulfate, a concentration of selenate that was subtoxic, while toxic levels of selenate produced far less derepression. The susceptibility of the tobacco cells to selenate toxicity was high under conditions of sulfur nutrition that derepress ATP sulfurylase, and low under conditions that repress ATP sulfurylase, in agreement with the idea that selenate acts via a functional sulfate assimilation pathway. Since it is known that selenate is incorporated into analogs of sulfur compounds, it is proposed that the tobacco cells synthesize the seleno-analog of the end product of the sulfate pathway responsible for repression, and the seleno-analog antagonizes the normal end product in the repression mechanism, the net result being derepression of ATP sulfurylase by selenate.

Adenosine Triphosphate↗
PubMed2000

Sulfite:Cytochrome c oxidoreductase from Thiobacillus novellus. Purification, characterization, and molecular biology of a heterodimeric member of the sulfite oxidase family.

Direct oxidation of sulfite to sulfate occurs in various photo- and chemotrophic sulfur oxidizing microorganisms as the final step in the oxidation of reduced sulfur compounds and is catalyzed by sulfite:cytochrome c oxidoreductase (EC ). Here we show that the enzyme from Thiobacillus novellus is a periplasmically located alphabeta heterodimer, consisting of a 40.6-kDa subunit containing a molybdenum cofactor and an 8.8-kDa mono-heme cytochrome c(552) subunit (midpoint redox potential, E(m8.0) = +280 mV). The organic component of the molybdenum cofactor was identified as molybdopterin contained in a 1:1 ratio to the Mo content of the enzyme. Electron paramagnetic resonance spectroscopy revealed the presence of a sulfite-inducible Mo(V) signal characteristic of sulfite:acceptor oxidoreductases. However, pH-dependent changes in the electron paramagnetic resonance signal were not detected. Kinetic studies showed that the enzyme exhibits a ping-pong mechanism involving two reactive sites. K(m) values for sulfite and cytochrome c(550) were determined to be 27 and 4 micrometer, respectively; the enzyme was found to be reversibly inhibited by sulfate and various buffer ions. The sorAB genes, which encode the enzyme, appear to form an operon, which is preceded by a putative extracytoplasmic function-type promoter and contains a hairpin loop termination structure downstream of sorB. While SorA exhibits significant similarities to known sequences of eukaryotic and bacterial sulfite:acceptor oxidoreductases, SorB does not appear to be closely related to any known c-type cytochromes.

Amino Acid Sequence↗
PubMed2001

Transcript expression in Saccharomyces cerevisiae at high salinity.

Transcript expression of Saccharomyces cerevisiae at high salinity was determined by microarray analysis of 6144 open reading frames (ORFs). From cells grown in 1 m NaCl for 10, 30, and 90 min, changes in transcript abundance >2-fold were classified. Salinity-induced ORFs increased over time: 107 (10 min), 243 (30 min), and 354 (90 min). Up-regulated, functionally unknown ORFs increased from 17 to 149 over this period. Expression patterns were similar early, with 67% of up-regulated transcripts after 10 min identical to those at 30 min. The expression profile after 90 min revealed different up-regulated transcripts (identities of 13% and 22%, respectively). Nucleotide and amino acid metabolism exemplified the earliest responses to salinity, followed by ORFs related to intracellular transport, protein synthesis, and destination. Transcripts related to energy production were up-regulated throughout the time course with respiration-associated transcripts strongly induced at 30 min. Highly expressed at 90 min were known salinity stress-induced genes, detoxification-related responses, transporters of the major facilitator superfamily, metabolism of energy reserves, nitrogen and sulfur compounds, and lipid, fatty acid/isoprenoid biosynthesis. We chose severe stress conditions to monitor responses in essential biochemical mechanisms. In the mutant, Deltagpd1/gpd2, lacking glycerol biosynthesis, the stress response was magnified with a partially different set of up-regulated ORFs.

Cell Division↗
PubMed2005

Molecular basis of intramolecular electron transfer in sulfite-oxidizing enzymes is revealed by high resolution structure of a heterodimeric complex of the catalytic molybdopterin subunit and a c-type cytochrome subunit.

Sulfite-oxidizing molybdoenzymes convert the highly reactive and therefore toxic sulfite to sulfate and have been identified in insects, animals, plants, and bacteria. Although the well studied enzymes from higher animals serve to detoxify sulfite that arises from the catabolism of sulfur-containing amino acids, the bacterial enzymes have a central role in converting sulfite formed during dissimilatory oxidation of reduced sulfur compounds. Here we describe the structure of the Starkeya novella sulfite dehydrogenase, a heterodimeric complex of the catalytic molybdopterin subunit and a c-type cytochrome subunit, that reveals the molecular mechanism of intramolecular electron transfer in sulfite-oxidizing enzymes. The close approach of the two redox centers in the protein complex (Mo-Fe distance 16.6 A) allows for rapid electron transfer via tunnelling or aided by the protein environment. The high resolution structure of the complex has allowed the identification of potential through-bond pathways for electron transfer including a direct link via Arg-55A and/or an aromatic-mediated pathway. A potential site of electron transfer to an external acceptor cytochrome c was also identified on the SorB subunit on the opposite side to the interaction with the catalytic SorA subunit.

Amino Acid Sequence↗
PubMed2006

An insight into the mechanism of human cysteine dioxygenase. Key roles of the thioether-bonded tyrosine-cysteine cofactor.

Cysteine dioxygenase is a non-heme mononuclear iron metalloenzyme that catalyzes the oxidation of cysteine to cysteine sulfinic acid with addition of molecular dioxygen. This irreversible oxidative catabolism of cysteine initiates several important metabolic pathways related to diverse sulfurate compounds. Cysteine dioxygenase is therefore very important for maintaining the proper hepatic concentration of intracellular free cysteine. Mechanisms for mouse and rat cysteine dioxygenases have recently been reported based on their crystal structures in the absence of substrates, although there is still a lack of direct evidence. Here we report the first crystal structure of human cysteine dioxygenase in complex with its substrate L-cysteine to 2.7A, together with enzymatic activity and metal content assays of several single point mutants. Our results provide an insight into a new mechanism of cysteine thiol dioxygenation catalyzed by cysteine dioxygenase, which is tightly associated with a thioether-bonded tyrosine-cysteine cofactor involving Tyr-157 and Cys-93. This cross-linked protein-derived cofactor plays several key roles different from those in galactose oxidase. This report provides a new potential target for therapy of diseases related to human cysteine dioxygenase, including neurodegenerative and autoimmune diseases.

Amino Acid Sequence↗
PubMed2003

Isolation and molecular characterization of thiosulfate-oxidizing bacteria from an Italian rice field soil.

In rice paddy soils an active cycling of sulfur compounds takes place. To elucidate the diversity of thiosulfate-oxidizing bacteria these organisms were enriched from bulk soil and rice roots by the most probable number method in liquid medium. From the MPN enrichment cultures 21 bacterial strains were isolated on solid mineral medium, and could be further shown to produce sulfate from thiosulfate. These strains were characterized by 16S rDNA analyses. The isolates were affiliated to seven different phylogenetic groups within the alpha- and beta-subclass of Proteobacteria. Two of these phylotypes were already described as S-oxidizers in this environment (Xanthobacter sp. and Bosea sp. related strains), but five groups represented new S-oxidizers in rice field soil. These isolates were closely related to Mesorhizobium loti, to Hydrogenophaga sp., to Delftia sp., to Pandoraea sp. or showed sequence similarity to a strain of Achromobacter sp.

Alphaproteobacteria↗
PubMed1958

Sodium exclusion and potassium retention by the red marine alga, Porphyra perforata.

Cells of the red marine alga, Porphyra perforata, accumulate potassium and exclude sodium, chloride, and calcium. Various metabolic inhibitors including dinitrophenol, anoxia, and p-chloromercuribenzoate partially abolish the cells' ability to retain potassium and exclude sodium. Iodoacetate induces potassium loss only in the dark; reduced sulfur compounds offer protection against the effects of p-chloromercuribenzoate; dinitrophenol stimulates respiration at concentrations which cause potassium loss and sodium gain. Following exposure to anoxia potassium accumulation and sodium extrusion take place against concentration gradients. These movements are retarded by sodium cyanide, but are stimulated by light. Sodium entry, following long exposure to 0.6 M sucrose, occurs rapidly with the concentration gradient, while potassium entry against the concentration gradient takes place slowly, and is prevented by cyanide.

Calcium↗
PubMed1986

1,2-Dithiol-3-thione analogs: effects on NAD(P)H:quinone reductase and glutathione levels in murine hepatoma cells.

The 1,2-dithiol-3-thiones are a class of five-membered cyclic sulfur compounds which have chemotherapeutic and chemoprotective properties. The parent 1,2-dithiol-3-thione nucleus and a series of six substituted analogs all induced NAD(P)H: quinone reductase (EC 1.6.99.2) activity and elevated glutathione levels in Hepa 1c1c7 murine hepatoma cells in culture thereby enhancing detoxification potential. These analogs included monosubstituted derivatives with phenyl, p-methoxyphenyl or 2-pyrazinyl groups at C-4 or C-5, and disubstituted compounds bearing phenyl or 2-pyrazinyl moieties at C-5 and an additional methyl group at C-4. This system can be used as an in vitro model for the study of the specificity and mechanism of action of the 1,2-dithiol-3-thiones as already demonstrated for several other classes of chemoprotective agents. The 1,2-dithiol-3-thiones also elevated quinone reductase and glutathione levels in the Hepa 1c1c7 cell mutants (BPrc1 and TAOBPrc1) that are defective in aryl hydrocarbon receptor functions. We conclude that the 1,2-dithiol-3-thiones are largely concerned with the stimulation of metabolic inactivation of electrophiles.

Animals↗
PubMed1987

Diallyl sulfide, a flavor component of garlic (Allium sativum), inhibits dimethylhydrazine-induced colon cancer.

Diallyl sulfide, a thioether found naturally in garlic, when given by gavage to C57BL/6J mice inhibited by 74% the incidence and reduced the frequency of colorectal adenocarcinoma induced by 20 weekly injections of 1,2-dimethylhydrazine. This result was predicted from a short-term assay measuring defects in nuclear morphology in mouse colon epithelial cells. This chemical is representative of a class of naturally occurring sulfur compounds with profound pharmacologic activity, one aspect of which may be cancer prevention.

1,2-Dimethylhydrazine↗
PubMed1988

Influence of thiocompounds on the metabolism of N-nitrosodiethylamine.

Diethyldithiocarbaminate (DDTC), mercaptoethanesulfonate (MESNA) and ethylxanthate (PEX) were tested for their influence on N-nitrosodiethylamine (NDEA) metabolism. The exhalation rate of 14CO2 released from [14C]NDEA was decreased by PEX, but not by MESNA or DDTC. The sulfur compounds led to an increased excretion of unchanged NDEA in urine in the order PEX greater than DDTC much greater than MESNA. The activity of NDEA-deethylase in liver microsomal system was decreased only after DDTC or PEX treatment. Glutathione content and glutathione-S-transferase activity were not affected significantly by any of the tested compounds. NDEA-induced single-strand breaks in liver cell DNA were inhibited after PEX treatment.

Animals↗