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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 11 (1972), S. 2634-2643 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 98 (1976), S. 1357-1364 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-072X
    Keywords: Thiobacillus versutus ; TCA cycle ; 13C incorporation ; PHB metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The disappearance of 2-13C-acetate and the subsequent incorporation of label into cellular metabolites were followed in denitrifying cells of Thiobacillus versutus by 13C NMR spectroscopy. In cells grown under acetate-limitation, the specific rate of consumption was idependent of the density of the cell suspension. An isotopic steady state was reached within 30 min if sufficient substrate was added to the cell suspension. In cells grown under nitrate-limitation, the consumption of 2-13C-acetate proceeded at a significantly lower rate. The decrease and final disappearance of 2-13C-acetate were accompanied by incorporation of 13C into glutamate, glutamine, and by the release of labeled HCO 3 − and CO2. The appearance of a broad resonance being the methyl endgroup of poly-3-hydroxybutyrate (PHB) was indicative for PHB mobilization during the incubation. The sequence of label incorporation and the distribution among the various carbon nuclei were consistent with the operation of the tricarboxylic acid cycle.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-072X
    Keywords: Key words     Aspergillus nidulans ; Carbon catabolite ; repression ; Arabinases ; Induction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract      The regulation of the syntheses of two arabinan-degrading extracellular enzymes and several intracellular l-arabinose catabolic enzymes was examined in wild-type and carbon catabolite derepressed mutants of Aspergillus nidulans. α-l-Arabinofuranosidase B, endo-arabinase, l-arabinose reductase, l-arabitol dehydrogenase, xylitol dehydrogenase, and l-xylulose reductase were all inducible to varying degrees by l-arabinose and l-arabitol and subject to carbon catabolite repression by d-glucose. With the exception of l-xylulose reductase, all were clearly under the control of creA, a negative-acting wide domain regulatory gene mediating carbon catabolite repression. Measurements of intracellular enzyme activities and of intracellular concentrations of arabitol and xylitol in mycelia grown on d-glucose in the presence of inducer indicated that carbon catabolite repression diminishes, but does not prevent uptake of inducer. Mutations in creA resulted in an apparently, in some instances very marked, elevated inducibility, perhaps reflecting an element of "self" catabolite repression by the inducing substrate. creA mutations also resulted in carbon catabolite derepression to varying degrees. The regulatory effects of a mutation in creB and in creC, two genes whose roles are unclear, but likely to be indirect, were, when observable, more modest. As with previous data showing the effect of creA mutations on structural gene expression, there were striking instances of phenotypic variation amongst creA mutant alleles and this variation followed no discernible pattern, i.e. it was non-hierarchical. This further supports molecular data obtained elsewhere, indicating a direct role for creA in regulating structural gene expression, and extends the range of activities under creA control.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-072X
    Keywords: Key wordsThiobacillus sp. W5 ; Sulfide oxidation ; Sulfur formation ; Flavocytochrome c ; Chlorobium ; limicola ; Chromatium vinosum ; Thiobacilli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel membrane-bound sulfide-oxidizing enzyme was purified 102-fold from the neutrophilic, obligately chemolithoautotrophic Thiobacillus sp. W5 by means of a six-step procedure. Spectral analysis revealed that the enzyme contains haem c and flavin. SDS-PAGE showed the presence of two types of subunit with molecular masses of 40 and 11 kDa. The smaller subunit contains covalently bound haem c, as was shown by haem staining. A combination of spectral analysis and the pyridine haemochrome test indicated that the sulfide-oxidizing heterodimer contains one molecule of haem c and one molecule of flavin. It appeared that the sulfide-oxidizing enzyme is a member of a small class of redox proteins, the flavocytochromes c, and is structurally most related to the flavocytochrome c sulfide dehydrogenase of the green sulfur bacterium Chlorobium limicola. The pH optimum of the enzyme is 8.6. At pH 9, the V max was 2.1 ± 0.1 μmol cytochrome c (mg protein)–1 min–1, and the K m values for sulfide and cytochrome c were 1.7 ± 0.4 μM and 3.8 ± 0.8 μM, respectively. Cyanide inhibited the enzyme by the formation of an N-5 adduct with the flavin moiety of the protein. On the basis of electron transfer stoichiometry, it seems likely that sulfur is the oxidation product.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-072X
    Keywords: Key wordsThiobacilli ; Chemolithoautotrophy ; Thiosulfate dehydrogenase ; Thiosulfate ; Tetrathionate ; Cytochrome c ; Respiratory chain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A periplasmic thiosulfate dehydrogenase (EC 1.8.2.2) was purified to homogeneity from the neutrophilic, obligately chemolithoautotrophic Thiobacillus sp. W5. A five-step procedure resulted in an approximately 2,300-fold purification. The purified protein had a molecular mass of 120 ± 3 kDa, as determined by gel filtration. It is probably a tetramer containing two different subunits with molecular masses of 33 ± 1 kDa and 27 ± 0.5 kDa, as determined by SDS-PAGE. UV/visible spectroscopy revealed that the enzyme contained haem c; haem staining showed that both subunits contained haem c. A haem c content of 4 mol per mol of enzyme was calculated using the pyridine haemochrome test. The pH optimum of the enzyme was 5.5. At pH 7.5, the Km and Vmax were 120 ± 10 μM and 1,160 ± 30 U mg–1, respectively. The absence of 2-heptyl-4-hydroquinoline-N-oxide (HQNO) inhibition for the oxidation of thiosulfate by whole cells suggested that the electrons enter the respiratory chain at the level of cytochrome c. Comparison with thiosulfate dehydrogenases from other Thiobacillus species showed that the enzyme was structurally similar to the thiosulfate dehydrogenase of the acidophilic, facultatively chemolithoautotrophic Thiobacillus acidophilus, but not to the thiosulfate dehydrogenases published for the obligately chemolithoautotrophic Thiobacillus tepidarius and Thiobacillus thioparus.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 29 (1985), S. 119-121 
    ISSN: 1432-1041
    Keywords: morphine ; rectal absorption ; oral absorption ; first-pass elemination ; relative bioavailability ; pH dependence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Rectal absorption of morphine HCl from aqueous vehicles at different pHs in man has been compared with an orally administered solution. Plasma concentrations of morphine were measured by electrochemical HPLC analysis after a single dose of 10 mg morphine HCl, in a cross-over study in 7 volunteers. Rectal absorption of morphine was dependent on pH, which could be explained as being due to pH partitioning. The absorption rate and bioavailability could be greatly improved, as compared to orally administered morphine, by adjusting the pH. It was concluded that a rectal solution adjusted to pH 7 to 8 provided an entirely adequate dosage form.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1041
    Keywords: Acne ; Erythromycin-zinc complex ; sebum excretion rate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract In a double-blind randomised study, 14 volunteers applied 4% erythromycin plus 1.2% zinc (Zineryt lotion) and 4% erythromycin lotions, each on half of the forehead twice daily for 3 months. The sebum output was evaluated at 3-week intervals using the photometric and the lipid-sensitive film methods. Evaluations of casual level (CL) and sebum excretion rate (SER) were made with a Sebumeter, and total area of lipid spots (TAS) was measured on Sebutapes. Compared to baseline values, the formulation of the erythromycin-zinc complex induced significant reductions in SER after 6 and 9 weeks, and in CL and TAS at 3, 6, 9 and 12 weeks. The mean reduction in TAS was over 20% for four successive 1-h samplings on completion of the study. Significant reductions in CL, SER and TAS were observed for the erythromycin-zinc formulation compared to the control lotion at 6 and 9 weeks, and also at 3 weeks for SER and TAS, and at 12 weeks for CL and TAS. This study indicates that sebum output is significantly reduced by the erythromycin-zinc complex. This reduction is theoretically beneficial for the acneic patient.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0983
    Keywords: Keywords Proteolytic degradation ; Expression ; Processing ; Glycosylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Transgenic filamentous fungi of the species Aspergillus niger, A. nidulans and A. awamori expressing and secreting Erwinia carotovora subsp. atroseptica pectate lyase 3 (PL3) were generated. Correct processing of the pre-enzyme was achieved using the A. niger pectin lyase A (PEL A) signal peptide. With the prepro-peptide of A. niger polygalacturonase II, secreted enzymes still possessed the 6- aa pro-sequence, indicating the importance of the conformation of the precursor protein for correct cleavage of the signal sequence. PL3 expression was markedly increased in media optimized for limited protease activity, and reached 0.4, 0.8 and 2.0 mg/l for expression in A. niger, A. awamori and A. nidulans, respectively. Glycans attached to the PL3 enzymes exhibited species-specific differences, and an increase of molecular mass coincided with reduced specific activities of the enzymes.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-0983
    Keywords: Proteolytic degradation ; Expression ; Processing ; Glycosylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transgenic filamentous fungi of the speciesAspergillus niger, A. nidulans andA. awamori expressing and secretingErwinia carotovora subsp.atroseptica pectate lyase 3 (PL3) were generated. Correct processing of the pre-enzyme was achieved using theA. niger pectin lyase A (PEL A) signal peptide. With the prepro-peptide ofA. niger polygalacturonase II, secreted enzymes still possessed the 6- aa pro-sequence, indicating the importance of the conformation of the precursor protein for correct cleavage of the signal sequence. PL3 expression was markedly increased in media optimized for limited protease activity, and reached 0.4, 0.8 and 2.0 mg/l for expression inA. niger, A. awamori andA. nidulans, respectively. Glycans attached to the PL3 enzymes exhibited species-specific differences, and an increase of molecular mass coincided with reduced specific activities of the enzymes.
    Type of Medium: Electronic Resource
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