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  • 1
    Electronic Resource
    Electronic Resource
    Mechanism of dissimilatory sulfite reduction by Desulfovibrio desulfuricans: purification of a membrane-bound sulfite reductase and coupling with cytochrome c3 and hydrogenase (1994)
    Springer
    Archives of microbiology 162 (1994), S. 255-260 
    Details
    ISSN: 1432-072X
    Keywords: Key words     Sulfite reductase ; Desulfoviridin ; Membranes ; Carbon monoxide ; Reconstitution ; Cytochrome c3 ; Hydrogenase ; Ion chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      The localization of the dissimilatory sulfite reductase in Desulfovibrio desulfuricans strain Essex 6 was investigated. After treatment of the cells with lysozyme, 90% of the sulfite reductase activity was found in the membrane fraction, compared to 30% after cell rupture with the French press. Sulfite reductase was purified from the membrane (mSiR) and the soluble (sSiR) fraction. On SDS-PAGE, both mSiR and sS iR exhibited three bands at 50, 45 and 11 kDa, respectively. From their UV/VIS properties (distinct absorption maxima at 391, 410, 583, 630 nm, enzymes as isolated) and the characteristic red fluorescence in alkaline solution, mSiR and sSiR were identified as desulfoviridin. Sulfite reductase (HSO3 –→H2S) activity was reconstituted by coupling of mSiR to hydrogenase and cytochrome c 3 from D. desulfuricans. The specific activity of mSiR was 103 nmol H2 min–1 mg–1, and sulfide was the major product (72% of theoretical yield). No coupling was found with sSiR under these conditions. Furthermore, carbon monoxide was used to differentiate between the membrane-bound and the soluble sulfite reductase. In a colorimetric assay, with photochemically reduced methyl viologen as redox mediator, CO stimulated the activity of sSiR significantly. CO had no effect in the case of mSiR. These studies documented th at, as isolated, both forms of sulfite reductase behaved differently in vitro. Clearly, in D. desulfuricans, the six electron conversion HSO3 –→H2S was achieved by a membrane-bound desulfoviridin without the assistance of artificial redox mediators, such as methyl viologen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301847
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanism of dissimilatory sulfite reduction by Desulfovibrio desulfuricans: purification of a membrane-bound sulfite reductase and coupling iwth cytochrome c 3 and hydrogenase (1994)
    Springer
    Archives of microbiology 162 (1994), S. 255-260 
    Details
    ISSN: 1432-072X
    Keywords: Sulfite reductase ; Desulfoviridin Membranes ; Carbon monoxide ; Reconstitution Cytochrome c 3 ; Hydrogenase ; Ion chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The localization of the dissimilatory sulfite reductase in Desulfovibrio desulfuricans strain Essex 6 was investigated. After treatment of the cells with lysozyme, 90% of the sulfite reductase activity was found in the membrane fraction, compared to 30% after cell rupture with the French press. Sulfite reductase was purified from the membrane (mSiR) and the soluble (sSiR) fractiion. On SDS-PAGE, both mSiR and sSiR exhibited three bands at 50, 45 and 11 kDa, respectively. From their UV/VIS properties (distinct absorption maxima at 391, 410, 583, 630 nm, enzymes as isolated) and the characteristic red fluorescence in alkaline solution, mSiR and sSiR were identified as desulfoviridin. Sulfite reductase (HSO3 -→H2S) activity was reconstituted by coupling of mSiR to hydrogenase and cytochrome c 3 from D. desulfuricans. The specific activity of mSiR was 103 nmol H2 min-1 mg-1, and sulfide was the major product (72% of theoretical yield). No coupling was found with sSiR under these conditions. Furthermore, carbon monoxide was used to diferentiate between the membrane-bound and the soluble sulfite reductase. In a colorimetric assay, with photochemically reduced methyl viologen as redox mediator, CO stimulated the activity of sSiR significantly. CO had no effect in the case of mSiR. These studies documented that, as isolated, both forms of sulfite reductase behaved differently in vitro. Clearly, in D. desulfuricans, the six electron conversion HSO3 -→H2S was achieved by a membranebound desulfoviridin without the assistance of artificial redox mediators, such as methyl viologen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301847
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Investigations on microbial sulfur respiration (1988)
    Springer
    Archives of microbiology 150 (1988), S. 72-77 
    Details
    ISSN: 1432-072X
    Keywords: Elemental sulfur ; Sulfane sulfur ; Trisulfide ; Sulfur-reducing bacteria ; Sulfur respiration ; Sulfur oxidoreductase ; Hydrogenase ; Rhodanese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The reduction of elemental or sulfane sulfur to hydrogen sulfide by eubacteria was investigated. Spirillum 5175 had the most active sulfur oxidoreductase. It could be cultivated with fumarate (F), elemental sulfur (S) or nitrate (N) as electron acceptor. Maximum activity was found for Spirillum 5175S but activity was also present in Spirillum 5175F and Spirillum 5175N, i.e. the sulfur oxidoreductase is a constitutive enzyme. It was localized in the membrane, and no activity was found in the cytoplasm in contrast to Desulfovibrio baculatus. Different procedures were applied for the measurement of the sulfur oxidoreductase activity. In the manometric assay hydrogenase was coupled to the sulfur oxidoreductase, and the uptake of dihydrogen was measured in the presence of elemental sulfur. Alternatively, H2S was assayed directly or was trapped in 12% NaOH and determined by the methylene blue procedure. Using 35S sulfur and 35S-labelled compounds both the substrate and H2S could be measured. A further increase in sensitivity was achieved using phenosafranin. It was reduced photochemically, and served as the electron donor to the sulfur oxidoreductase, i.e. no hydrogenase was required. This was an important result in view of the fact that not all sulfur-reducing bacteria contain hydrogenase. However, in those cases the hydrogenase isolated from Clostridium pasteurianum could be coupled to the sulfur oxidoreductase. Among the different forms of elemental sulfur Janek sulfur gave the best results in terms of activity and reproducibility. The reduction of elemental sulfur to hydrogen sulfide had a pH optimum at pH 8.7–8.9. There was always a lag-phase which was pH-dependent. During this period the turbidity of the solution changed. Addition of thiols, such as GSH, shortened the lag-phase and caused an increase in activity of the sulfur oxidoreductase. In the presence of p-chloromercuribenzenesulfonic acid the reaction rate decreased significantly. Comparable reaction rates and activity values of the sulfur oxidoreductase in Spirillum 5175F were obtained with organic trisulfides, RS-S-SR. In contrast to elemental sulfur RS-S-SR are well-defined chemical compounds suitable for quantitative and mechanistic investigations. Labelling the central sulfur of RS-S-SR with 35S gave a satisfactory recovery of the total radioactivity in form of (35S) H2S in our assay. Trisulfides were shown to be formed as reactive intermediates in bacteria. This process required the sulfur transferase rhodanese which was present in Spirillum 5175, or other sulfur-reducing eubacteria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00409720
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The copper site in nitrous oxide reductase (1990)
    Springer
    BioMetals 3 (1990), S. 103-109 
    Details
    ISSN: 1572-8773
    Keywords: Nitrous oxide reductase ; Cytochrome c oxidase ; Cu-Cu interaction ; Mixed-valence complex ; Denitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The properties of the novel copper enzyme nitrous oxide reductase from denitrifyingPseudomonas stutzeri are described. Multifrequency electron paramagnetic resonance spectroscopy is used to characterize the various forms of the enzyme. The features observed at 2.4, 3.4, 4.5, 9.31 and 35 GHz are explained by a mixed-valence \s[Cu(1.5)\3. Cu(1.5)\s]S=\12 species with the unpaired electron delocalized between the two Cu nuclei. This site is also present in the catalytically inactive derivative of nitrous oxide reductase which was obtained from a transposon Tn5-induced mutant with defective chromophore biosynthesis. The resemblance of the low-frequency electron paramagnetic resonance spectra to the spectra for the so-called CuA of cytochromec oxidase can be taken as a first indication that the CuA may have a structural and electronic arrangement similar to the electron-paramagnetic-resonance-detectable copper in nitrous oxide reductase. Results from oxidation/reduction experiments, and from a quantitative determination of sulfhydryl and disulfide residues in the various forms of nitrous oxide reductase, suggest the involvement of the redox-couple cysteine/cystine in the structural organization of the active site of nitrous oxide reductase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01179514
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    Paper (German National Licenses)
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