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  • Industrial Chemistry and Chemical Engineering  (8)
  • Clostridium acidiurici  (3)
  • 1
    Digitale Medien
    Digitale Medien
    Selenium requirement for active xanthine dehydrogenase from Clostridium acidiurici and Clostridium cylindrosporum (1979)
    Springer
    Archives of microbiology 121 (1979), S. 255-260 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Purine fermentation ; Xanthine dehydrogenase ; Selenium ; Tungsten ; Molybdenum ; Clostridium acidiurici ; Clostridium cylindrosporum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The xanthine dehydrogenase of Clostridium acidiurici and C. cylindrosporum was assayed with methyl viologen as acceptor. In C. acidiurici the basal activity level was about 0.3 μmol/min x mg of protein. Cells grown on uric acid in the presence of 10-7 M selenite showed a 14-fold increase in xanthine dehydrogenase activity, which decreased with higher selenite concentrations (10-5 M). The supplementation with 10-7 M molybdate or tungstate was without effect. High concentrations of tungstate decreased the xanthine dehydrogenase if selenite was also present. In comparison, high concentrations of molybdate affected only a small decrease in activity level at the optimal concentration for selenite and relieved to some degree the inhibitory effect of 10-5 M selenite. With hypoxanthine and xanthine as substrates for growth again only the addition of selenite was necessary to show a similar increase in xanthine dehydrogenase activity. C. acidiurici could be grown in a mineral medium. Both xanthine dehydrogenase and formate dehydrogenase exhibited the highest level of activity if selenite and tungstate were present in that medium. In C. cylindrosporum the basal activity level of xanthine dehydrogenase was about 0.95 μmol/min x mg of protein. The addition of 10-7 M selenite to the growth medium increased the activity level about 3-fold, but the highest level (3.7 U/mg) was reached if 10-7 M molybdate was also added. The presence of tungstate resulted in a decreased enzyme activity.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00425064
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  • 2
    Digitale Medien
    Digitale Medien
    Accumulation and incorporation of 185W-tungsten into proteins of Clostridium acidiurici and Clostridium cylindrosporum (1987)
    Springer
    Archives of microbiology 147 (1987), S. 295-299 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Clostridium acidiurici ; Clostridium cylindrosporum ; Tungsten uptake ; Molybdate antagonism ; Formate dehydrogenase ; Tungsten-binding-storage protein
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Uptake of tungstate by growing cells was unaffected by the presence of molybdate in Clostridium cylindrosporum, whereas in C. acidiurici the accumulation was decreased by molybdate at 10-6 mol/l tungstate and higher concentrations. The labelling pattern of soluble proteins by 185W-tungsten indicated after gel chromatography the presence of three different tungstoproteins in both bacteria. Formate dehydrogenase activity always eluted at a maximum of tungsten labelling. The incorporation of tungsten into formate dehydrogenase containing fractions and a possible tungsten-binding-storage protein was independent of the presence of excess molydate pointing to a genuine role for tungstate in these bacteria.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00463491
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  • 3
    Digitale Medien
    Digitale Medien
    Comparative studies on physiology and taxonomy of obligately purinolytic clostridia (1984)
    Springer
    Archives of microbiology 138 (1984), S. 345-353 
    Details
    ISSN: 1432-072X
    Schlagwort(e): Clostridium acidiurici ; Clostridium cylindrosporum ; Clostridium purinolyticum ; Purine metabolism ; Selenite ; Antibiogram ; DNA homology ; Taxonomy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Eleven strains of obligately purinolytic clostridia have been studied with respect to their assignment to the three type strains of Clostridium acidiurici, C. cylindrosporum, and C. purinolyticum. DNA/DNA-hybridization proved to be the method of choice for differentiation whereas phenotypic characteristics such as spore morphology, substrate spectra, nutritional requirements, product formation, and sensitivity against various antibiotics did not allow unequivocal identification. All strains depended on selenite for growth.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00410902
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  • 4
    Digitale Medien
    Digitale Medien
    Silicon-modified carbohydrate surfactants IX: dynamic wetting of a perfluorinated solid surface by solutions of a siloxane surfactant above and below the critical micelle concentration (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 843-853 
    Details
    ISSN: 0268-2605
    Schlagwort(e): carbohydrate-modified phenylsiloxane ; surfactants ; wetting behaviour ; superspreading ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The dynamic wetting behaviour on a perfluorinated, low-energy solid has been investigated for a carbohydrate-modified phenylsiloxane surfactant. The surfactant concentration, the rate of interface generation and the [solid/liquid interface area] : [liquid/vapour interface area] ratio were varied systematically. Dynamic data for the liquid/vapour (γlv) and solid/liquid (γsl) interfacial tension as well as their Lifshitz-van der Waals and donor-acceptor contributions were determined under strictly controlled conditions. Since γsl reacts sensitively to variations of the surfactant concentration and the rate of interface generation, the covering of the liquid/non-polar solid interface is assumed to be a spreading limiting factor. The corresponding γlv values remain constant and close to those obtained under equilibrium conditions. Copyright © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants III: Cationic and Anionic Compounds (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 523-538 
    Details
    ISSN: 0268-2605
    Schlagwort(e): silicon-modified ; carbohydrate ; surfactant ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ionic siloxanyl-modified carbohydrate surfactants have been synthesized by alkylation/esterification of precursors containing tertiary amino functions. Depending on the reaction strategy, the siloxanyl moiety is part of the alkylating agent or the substrate. Polyhydroxylated tertiary amines can be quaternized by siloxanyl-modified chloroacetic acid esters or epoxysiloxanes in the presence of glacial acetic acid. The esterification of tertiary amines bearing carbohydrate and siloxanyl subunits by cyclic acid anhydrides yields, after neutralization, carboxylate salts. The reaction of hydroxyl groups and sulfamic acid leads to sulfates. The new substances were characterized by means of 13C NMR spectroscopy, gas chromatography, elemental analysis and their solubility profile. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Silicon-modified carbohydrate surfactants. IV. The impact of substructures on the wetting behaviour of siloxanyl-modified carbohydrate surfactants on low-energy surfaces (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 617-632 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxanyl-modified ; carbohydrate ; surfactant ; wetting behaviour ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The siloxanyl-modified carbohydrate surfactants investigated consist of the four structural elements: (1) siloxanyl moiety; (2) spacer; (3) carbohydrate unit; and (4) modifying element. By static surface tension (γsν  -  γsβ α) measurements the contact angles of the aqueous surfactant solutions above the critical micelle formation concentration (cmc) on nonpolar perfluorinated surfaces (FEP® plate) were determined. Although the siloxanyl units were found to have a high capacity to level out the interfacial properties, both surface tension and wetting tension react independently to defined changes in the chemical structure of the surfactant molecules. The results of spreading experiments on polyproylene show good correlation with the dependences found by wetting meaurements. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants V: The Wetting Behaviour of Low-Molecular-Weight Siloxane, Carbosilane, Silane and Polysilane Precursors on Low-Energy Surfaces (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 645-657 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxane ; surface tension ; control angle ; interfacial tension ; wetting tension ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The surface tensions, wetting tensions, contact angles and solid/liquid interfacial tensions of defined siloxanes as well as those of analogous carbosilanes, polysilanes and neopentyl substituted silanes were determined. The wetting experiments were carried out on a glass plate coated with perfluoroalkyl methacrylate (FC 722®). The siloxanes possess the lowest surface tensions. Due to the presence of oxygen atoms in the siloxane backbone, a donor-acceptor portion (γ+/-lv) of the surface tension of about 1-2 mN/m was determined. The solid/liquid interfacial tension also contains a donor-acceptor portion (γ+/-sl). Its value is almost identical to that of γ+/-lv. The γ+/-sl differences between individual molecules of the same surface tension are responsible for contact angle differences of up to 4°. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants I: Synthesis of Siloxanyl Moieties Containing Straight-chained Glycosides and Amides (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 421-435 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxanes ; carbohydrate modified ; surfactants ; saccharide ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New siloxanyl-modified carbohydrate surfactants of the amide and glycoside type have been synthesized by coupling between defined as well as higher-molecular-weight siloxanes and carbohydrate structures via spacers of different lengths and hydrophilic power. Linear and branched monohydrogen di-, tri-, tetra- and penta-siloxanes and polyhydrogen siloxanes as well as mono- and di-saccharide lactone structures have been found to be good starting materials for the synthesis of amides, often in quantitative yield, whereas glycosides had to be prepared in low-yield multistep sequences including protection/deprotection steps. Selected strategies were applied to polysiloxanes yielding quantitatively a broad variety of carbohydrate-modified comb-like structures. The new substances were characterized by means of 13C NMR spectroscopy, GC, capillary GC, GC-MS coupling and elemental analysis.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants II: Siloxanyl Moieties Containing Branched Structures (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 437-450 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxanes ; surfactant ; carbohydrate ; amino ; regioselective ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Branched siloxanyl-modified carbohydrate surfactants have been synthesized by coupling mono-, di- and poly-functional siloxanes to carbohydrate units either via a branched spacer or by attaching a separate modifying element to a straight-chained structure. Hydrophilic as well as extremely hydrophobic elements have been incorporated successfully. Siloxanyl-modified carbohydrates bearing a secondary amino function were alkylated in regioselective reactions by different epoxides ranging from glycidol- to siloxanyl-modified allyl glycidyl ether derivatives. Alternatively, carbohydrate-modified piperazinyl structures yielded cyclic subunits after alkylation. Structures bearing two identical hydrophilic groups are accessible by alkylation of carbohydrate-modified bisamides. The derivatives synthesized were characterized by means of GC, NMR and elemental analysis.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Silicon-modified carbohydrate surfactants VI: Synthesis of carbosilane, silane, polysilane and non-permethylated siloxane derivatives; the wetting behaviour of epoxy-modified precursor liquids on non-polar surfacesIn remembrance of Professor Dr Edwin Hengge (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 47-58 
    Details
    ISSN: 0268-2605
    Schlagwort(e): surfactants ; carbohydrate ; carbosilane ; silane ; wetting ; surface tension ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of carbohydrate surfactants bearing carbosilane, silane, polysilane and non-permethylated siloxane moieties is described. These surfactants consist of three structural elements: (1) a silicon-containing moiety, (2) a spacer and (3) a carbohydrate unit. Additionally two different types of mixed structures have been synthesized: (a) single-chained carbosilane-siloxane surfactants and (b) double-chained combinations of carbo- silanes, silanes and siloxanes. The wetting behaviour of the key intermediates, the allyl glycidyl derivatives, has been investigated by static surface tension (γlv, σ) and wetting tension (γsv-γsl, α) measurements on a non-polar perfluorinated surface (FEP® plate). The contact angles obtained for these pure liquids are not a linear function of the surface tension but depend on the polarity of the substructures. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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