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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 112 (1977), S. 283-285 
    ISSN: 1432-072X
    Keywords: Wine yeasts ; Sulfur metabolism ; Regulation ; Sulfate uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Five different strains of wine yeasts were investigated with respect to active uptake of [35S] sulfate and its regulation by methionine. Considerable differences exist between “low” and “high” sulfite-producing strains in the initial velocity of sulfate uptake. Further differences were established in repression of sulfate permease by l-methionine, most evident in a total lack of repression in one of the “high” sulfite producers. These findings explain in part variable sulfite and sulfide formation.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 121 (1979), S. 251-253 
    ISSN: 1432-072X
    Keywords: Wine yeasts ; Sulfite formation ; Sulfur metabolism ; OAS/OAHS-sulfhydrylase regulation ; Serine sulfhydrase regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Four strains of wine yeasts of two different species (Saccharomyces cerevisiae var. ellipsoideus and Saccharomyces bayanus) were investigated with respect to the influence of various sulfur compounds on the formation of O-acetylserine sulfhydrylase, O-acetylhomoserine sulfhydrylase and serine sulfhydrase. The specific enzyme activities were followed over a growth period of 96 h. In the presence of sulfate, sulfite and djencolic acid during exponential growth, a moderate increase of O-acetylserine sulfhydrylase and O-acetylhomoserine sulfhydrylase activities was recognized. In three strains cysteine and methionine prevented this derepression. At the end of the exponential growth phase, biosynthesis of these two enzymes was suppressed again. Serine sulfhydrase showed a modified regulation which indicates that its synthesis and the synthesis of O-acetylserine and O-acetylhomoserine sulfhydrylases are not coordinated.
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  • 3
    ISSN: 1432-072X
    Keywords: Rhodopseudomonas globiformis ; Thiosulfate assimilation ; Thiosulfate ; Tetrathionate ; Thiosulfate: acceptor oxidoreductase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhodopseudomonas globiformis is able to assimilate both sulfur moieties of thiosulfate. During growth on 35S-labelled thiosulfate the amino acids cysteine, homocysteine and methionine were labelled. The bulk of thiosulfate, however, was oxidized to tetrathionate and accumulated in the medium. A thiosulfate: acceptor oxidoreductase was partially purified and characterized. The enzyme oxidized thiosulfate to tetrathionate in the presence of ferricyanide. A c-type cytochrome isolated from this organism was reduced by this enzyme.
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  • 4
    ISSN: 1432-072X
    Keywords: Rhodospirillaceae ; Rhodopseudomonas globiformis ; Sulfate assimilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhodopseudomonas globiformis is able to grow on sulfate as sole source of sulfur, but only at concentrations below 1 mM. Good growth was observed with thiosulfate, cysteine or methionine as sulfur sources. Tetrathionate supported slow growth. Sulfide and sulfite were growth inhibitory. Growth inhibition by higher sulfate concentrations was overcome by the addition of O-acetylserine, which is known as derepressor of sulfate-assimilating enzymes, and by reduced glutathione. All enzymes of the sulfate assimilation pathway. ATP-sulfurylase, adenylylphosphate-sulfotransferase, thiosulfonate reductase and O-acetylserine sulfhydrylase are present in R. globiformis. Sulfate was taken up by the cells and the sulfur incorporated into the amino acids cysteine, methionine and homocysteine. It is concluded, that the failure of R. globiformis to grow on higher concentrations of sulfate is caused by disregulation of the sulfate assimilation pathway. Some preliminary evidence for this view is given in comparing the activities of some of the involved enzymes after growth on different sulfur sources and by examining the effect of O-acetylserine on these activities.
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  • 5
    ISSN: 1432-072X
    Keywords: Rhodopseudomonas sulfoviridis ; Assimilatory sulfur metabolism ; Sulfur assimilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhodopseudomonas sulfoviridis is unable to grow with sulfate as sole sulfur source. Radioactively labelled sulfate is not incorporated into the cells. Growth only occurs in the presence of reduced sulfur compounds, such as sulfide, thiosulfate, elemental sulfur and cysteine. ATP sulfurylase, adenylylsulfate kinase, O-acetylserine sulfhydrylase and cysteine desulfhydrase are present. Adenylylsulfate sulfotransferase and thiosulfonate reductase are lacking. The enzymes of the sulfate-activating system are not derepressed by O-acetylserine.
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  • 6
    ISSN: 1432-072X
    Keywords: Chlorobium vibrioforme ; Cytochrome c-555 ; Rubredoxins ; Ferredoxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The non-thiosulfate-utilizing green sulfur bacterium Chlorobium vibrioforme contains only one soluble c-type cytochrome (c-555) besides two rubredoxins and ferredoxin. These electron transfer proteins were highly purified by ion exchange chromatography and gel filtration. Cytochrome c-555 is a small and weakly basic hemoprotein with an isoelectric point at pH 7.3, a redoxpotential of + 80 mV, and a molecular weight of 11,500 (±500) determined by electrophoresis on sodium dodecylsulfate polyacrylamide gel, and of 11,000 by gel filtration on Sephadex G-75. Cytochrome c-555 shows maxima at 412.5 nm in the oxidized form, and three maxima in the reduced state (α-band at 555 nm with a shoulder at 551 nm, β-band at 523 nm, and γ-band at 418 nm). The best purity index (A280/A418) obtained was 0.15. The two rubredoxins (rub I and rub II) are acidic small proteins and both have the same molecular weight of 8,100 estimated by gel filtration on Sephadex G-75 and show the same maxima at 370 nm, 492 nm, and 575 nm in the oxidized form but differ only in their isoelectric points at pH 2.9 (rub I) and at pH 2.7 (rub II). The best purity index obtained (A280/A370) was 3.27 for rub I and 3.57 for rub II respectively. Both rubredoxins contain one iron atom per molecule. Ferredoxin is also an acidic protein with an isoelectric point at pH 2.5 and shows maxima at 300 nm and 380 nm in the oxidized form.
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  • 7
    ISSN: 1432-072X
    Keywords: Ectothiorhodospira shaposhnikovii ; Bacterial ferredoxin ; High potential iron sulfur protein (HIPIP)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In addition to several cytochromes three iron sulfur proteins were detected in mixotrophically grown cells of Ectothiorhodospira shaposhnikovii, a member of the Chromatiaceae. They were identified as a bacterial ferredoxin and two high potential iron sulfur proteins (HIPIPs). The two HIPIPs were purified and characterized. They were named according to their differing retention times on a DEAE-cellulose column using a continuous NaCl gradient: “early” and “late” HIPIP. The HIPIPs contain 4 mol of non-heme iron and 4 mol of acid labile sulfur per mol protein. Under the conditions of purification the “early” HIPIP (E m, 7+270 mV) was present in a semi-reduced state. Using ion-exchange chromatography the “early” HIPIP could be split into a reduced green-brown (pI=3.7) and an oxidized red-brown (pI=3.9) fraction. The “late” HIPIP (pI=3.8) showed a midpoint potential of only+155 mV, the lowest redox potential of a HIPIP described so far.
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  • 8
    ISSN: 1432-072X
    Keywords: Ectothiorhodospira halochloris ; Cytochrome c-551 ; Sulfide oxidation ; Elemental sulfur reduction ; Polysulfide ; Sulfur metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ectothiorhodospira halochloris grows photoheterotrophically with a variety of sulfur sources. During sulfide oxidation to elemental sulfur considerable amounts of polysulfides may be accumulated transiently. When grown on elemental sulfur no sulfate was produced by oxidation, but sulfide and polysulfide were formed by reduction. Only one soluble cytochrome c-551 was isolated and purified. It was a small acidic hemeprotein with a molecular weight of 6,300, an isoelectric point of 3.1 and a redox potential of-11 mV at pH 7.0. It showed three absorption maxima in the reduced state (α=551 nm; β=523 nm; γ=417 nm). The addition of various c-type cytochromes to a suspension of spheroplasts stimulated the velocity of sulfide oxidation. This stimulation was best with the small acidic cytochromes from E. halochloris or Ectothiorhodospira abdelmalekii. Sulfide oxidation was stopped by several uncoupling agents, ionophores and electron transport inhibitors. Antimycin A, rotenone and cyanide had no effect on sulfide oxidation.
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  • 9
    ISSN: 1432-072X
    Keywords: Rhodobacter sulfidophilus ; ATP sulfurylase ; Sulfate assimilation ; Sulfate activation ; Rhodospirillaceae ; Purple nonsulfur bacteria ; Rhodopseudomonas sulfidophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rhodobacter sulfidophilus, R. capsulatus, R. sphaeroides, Rhodospirillum rubrum, Rhodopseudomonas palustris, R. viridis and Rhodocyclus gelatinosus were found to be able to synthesize adenylylsulfate and 3′-phosphoadenylylsulfate from sulfate and ATP. The presence of ATP sulfurylase was proven for the soluble protein fractions of all these species. ADP sulfurylase was not found. ATP sulfurylase was purified from R. sulfidophilus. Its molecular weight was 290,000. The enzyme is stabilized by magnesium ions and elevated salinities. The optimal pH was 8.0, activity was found between pH 6.8 and 9.4. The enzyme is inactivated at temperatures above 40°C. Kinetic studies resulted in K m(ATP)=0.26 mM, K m(sulfate)=0.33 mM; K i(AMP)-2.1 mM, K i(ADP)=1.15 mM; K i(APS)=0.8 μM; K i(sulfite)=0.4. mM; K i(sulfide)=0.66mM.
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  • 10
    ISSN: 1432-072X
    Keywords: Chromatophores ; Electron transport ; NAD photoreduction ; Photosynthesis ; Phototrophic bacteria ; Rhodobacter sulfidophilus ; Sulfide oxidation ; Ubiquinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chromatophores isolated from the marine phototrophic bacterium Rhodobacter sulfidophilus were found to photoreduce NAD with sulfide as the electron donor. The apparent K m for sulfide was 370 μM and the optimal pH was 7.0. The rate of NAD photoreduction in chromatophore suspensions with sulfide as the electron donor (about 7–12 μM/h·μmol Bchl) was approximately onetenth the rate of sulfide oxidation in whole cell suspensions. NAD photoreduction was inhibited by rotenone, carbonyl cyanide-m-chlorophenylhydrazone, and antimycin A. Sulfide reduced ubiquinone in the dark when added to anaerobic chromatophore suspensions. These results suggest that electron transport from sulfide to NAD involves an initial dark reduction of ubiquinone followed by reverse electron transport from ubiquinol to NAD mediated by NADH dehydrogenase.
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