Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 31 (1983), S. 934-938 
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 79 (1971), S. 12-24 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung 1. In 4 von 9 untersuchten Stämmen von Bacillus sphaericus ließ sich eine l-Valin-Carboxylyase nachweisen. 2. Einige Eigenschaften des Enzyms wurden an Acetonpräparaten von B. sphaericus ATCC 245 näher untersucht. Die Decarboxylase reagiert substratunspezifisch mit folgenden Aminosäuren: Valin, Norvalin, Leucin, 2-Amino-n-buttersäure, Norleucin, Isoleucin, Methionin, Alanin und Phenylalanin. Bei gleichzeitigem Angebot zweier Substrate läßt sich kein additiver Effekt feststellen. 3. Das pH-Optimum der Enzymkatalyse liegt bei pH 7,7–7,9, das Temperaturoptimum zwischen 50 und 60°C. 4. Die Decarboxylase wird durch Pyridoxalphosphat (PLP), in geringerem Maße auch durch Pyridoxal, aktiviert. Ohne Zusatz von PLP nimmt die Decarboxylierungsrate stetig ab, und zwar bei Leucin sehr viel schneller als bei Valin; die Decarboxylierung von Valin wird durch Leucin gehemmt. 5. Carbonyl- und SH-Gruppenreagentien hemmen die Decarboxylase. PLP schützt das Enzym in gewissem Umfang gegen die bei Leucin stärker als bei Valin progressiv zunehmende Hemmung durch Jodacetat, kann aber eine bereits eingetretene Inaktivierung nicht wieder aufheben. 6. Die Enzymaktivität ist am höchsten in ganz jungen Kulturen von Bacillus sphaericus; schon zu Beginn des exponentiellen Wachstums fällt sie steib ab.
    Notes: Summary 1. The occurrence of a l-valine carboxy-lyase in Bacillus sphaericus has been demonstrated. The enzyme was found to occur in four out of nine strains tested. 2. Some properties of the decarboxylase were studied in detail using acetonedried cells of B. sphaericus ATCC 245. The substrate-unspecific enzyme decarboxylates the following amino acids: valine, norvaline, leucine, 2-amino n-butyric acid, norleucine, isoleucine, methionine, alanine and phenylalanine. When two substrates are present simultaneously no additive effects are detected. 3. The pH optimum for the reactions is about pH 7.7–7.9, the optimum temperature between 50 and 60°C. 4. The enzyme is activated by pyridoxal phosphate (PLP) and, to a lower extent, by pyridoxal. In the absence of added PLP the rate of decarboxylation decreases continuously. The inactivation occurs more rapidly during decarboxylation of leucine than of valine; added leucine progressively inhibits valine decarboxylation. 5. The decaroxylations are sensitive to reagents known to combine with carbonyl and — SH groups. PLP protects the enzyme to some extent against a progressive inhibition by iodoacetate which is stronger with leucine than with valine. It doesn't, however, reverse inactivation already established. 6. The enzyme activity is highest in very young cultures of Bacillus sphaericus. It decreases rapidly in the early exponential phase of growth.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 56 (1967), S. 1-8 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The degradation of tryptophan (Try) and some of its potential intermediates has been studied in nodule bacteria (Rhizobium leguminosarum Frank, ATCC 10324). In feeding experiments with washed suspensions the following degradation products of Try could be identified by thin-layer chromatography: indolyl-3-pyruvic acid (IBS); indolyl-3-acetic acid (IES); β-(indolyl-3)-lactic acid (IMS); indole-carboxylic acid-(3) (ICS); β-(indolyl-3)-ethanol (β-IÄ); indole-aldehyde-(3) (IAld); indolyl-3-acetaldehyde (IAAld); Nα-acetyl-tryptophan (Ac-Try). An active Try-transaminase leading to the formation of IBS has been demonstrated. Phenylpyruvic acid as well as α-ketoglutaric acid served as amino group acceptors. The breakdown of Try was followed quantitatively by using C-14(2-alanyl-) D,L-tryptophan. After 16 hrs nearly 16% of the original radioactivity was found in the ether-extractable material. IES and IMS were formed in much the highest concentrations. Indole-3-acetonitrile (IAN), although not a Try-metabolite in Rhizobium leguminosarum was converted to IES via indole-3-acetamide (IAAm). The following physiological pathways in the breakdown of Try in Rhizobium leguminosarum have been confirmed: Try → Ac-Try and IBS; IBS → IAAld; IAAld → β-IÄ and IES; no further degradation of IES was observed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 64 (1969), S. 239-243 
    ISSN: 1432-072X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Zusammenfassung Acetonpräparate von Proteus vulgaris und Bacillus sphaericus ATCC 245 sowie in geringerem Umfang Umpflanzkulturen der Pilze Claviceps purpurea und Penicillium nigricans decarboxylieren L-Methionin zu 3-Methylmeracaptopropylamin (MMPA). Die Identität des Decarboxylierungsproduktes mit authentischem MMPA wurde durch chromatographischen Vergleich und übereinstimmende Schmelzpunkte der Pikrate und DNP-Derivate gesichert. Es wird angenommen, daß die Methionindecarboxylierung durch eine substratunspezifische Decarboxylase für neutrale Aminosäuren katalysiert wird. Das entsprechende Enzym bei P. vulgaris wäre die von Ekladius et al. (1957) beschriebene Valin/Leucin-Carboxy-lyase (E.C. 4.1.1.14).
    Notes: Summary Acetone powders of Proteus vulgaris and Bacillus sphaericus ATCC 245 as well as to some lower extent washed suspensions of the fungi Claviceps purpurea and Penicillium nigricans decarboxylate L-methionine to 3-methyl-mercaptopropylamine (MMPA). Identity of the product of decarboxylation with authentic MMPA was proved by chromatographic comparison and conformance of the melting points of the picrates and DNP-derivatives. It is assumed that the decarboxylation of methionine is catalyzed by a substrate-unspecific decarboxylase of neutral amino acids. The respective enzyme in P. vulgaris would be the valine/leucine-carboxylyase (E.C. 4.1.1.14) already described by Ekladius et al. (1957).
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Cerium oxides are used as surrogates for plutonium oxides because of the similarities in their thermodynamic properties. In this study, the stability limits of both CeGaO3 and PuGaO3 with respect to the partial pressure of oxygen and temperature have been predicted by theoretical calculations. Using the results of the calculations as guidance, mixtures of CeO2 and Ga2O3 have been prepared and thermally treated at 1273, 1473, and 1673 K, in atmosphere of air, argon, or Ar–6% H2. In the samples annealed under low oxygen partial pressures, the CeGaO3 perovskite-type compound was identified. Based on Rietveld structure refinement, the orthorhombic space group (Pnma, 62) was confirmed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Neutron diffractometry and X-ray diffractometry were used to characterize the cation disorder and vacancy distribution in nonstoichiometric spinel, MgO·xAl2O3, where x greaterthan equal to 1.0. Both synthetic and natural samples were examined. Least-squares refinements of integrated intensities for single crystals and Rietveld profile refinements for powders yielded the average scattering “power” from tetrahedral and octahedral sites within the almost-perfect cubic close-packed oxygen sublattice. The cation disorder was calculated assuming models in which the vacancies resided on tetrahedral, octahedral, or both types of sites. No degree of cation disorder was consistent with the tetrahedral vacancy model, and vacancies most likely resided on octahedral sites.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    facet.materialart.
    Unknown
    Berlin : Periodicals Archive Online (PAO)
    Neue Zeitschrift für systematische Theologie und Religionsphilosophie. 32 (1990) 237 
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 72 (1999), S. 174-177 
    ISSN: 1432-1246
    Keywords: Key words Occupational exposure ; Sevoflurane ; Sedation ; Regional anesthesia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Objectives: In a field study we evaluated the workplace pollution occurring during conscious sedation with sevoflurane in adults. Methods: Sevoflurane was given in 100% oxygen at a fresh gas flow rate of 3 l/min via a nasal mask. This was conducted in 25 patients scheduled for surgical procedures performed under regional anesthesia. Trace concentrations of sevoflurane were directly measured every minute in the breathing zone by means of a photoacoustic infrared spectrometer in an operating room with an air turnover of 20 changes/h. Results: The mean sedation time was 49.6 ± 20.4 min. The average vaporizer setting of the anesthesia machine was 1.63 ± 0.6 vol%, resulting in a patient's mean end-tidal sevoflurane concentration of 0.78 ± 0.2 vol%. The 8-h time-weighted average was calculated to be 0.58 ppm sevoflurane. Conclusions: The trace gas concentrations were low and comparable with values obtained under inhalation induction in adults and children. Although no occupational standard for sevoflurane is currently defined, the measured values are clearly under the standards recommended for enflurane (20 ppm) and isoflurane (10 ppm) by the European health authorities. We conclude that the new anesthesiologic method of conscious sedation with sevoflurane in adults using a nasal mask would not result in a violation of occupational standards, provided that the future value set for sevoflurane would be similar to those recommended for isoflurane or enflurane.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1423-0445
    Keywords: Key words. pyrrolizidine alkaloids, sequestration, chemical defense, alkaloid metabolism, N-oxidation, Mechanitis polymnia, Ithomiinae, Nymphalidae, Lepidoptera.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary. Tracer feeding studies with radioactively labeled pyrrolizidine alkaloids (PAs) were performed to attain experimental information about the specificity and mechanisms of uptake, metabolism and storage of PAs in the alkaloid sequestering ithomiine butterfly Mechanitis polymnia. Adult butterflies easily ingest the tracers offered dissolved in a saturated sugar solution. Feeding of [14C]rinderine (free base) confirmed that M. polymnia is well adapted to sequester and maintain PAs of the lycopsamine type. Approximately 80% of the ingested radioactivity can be recovered in methanol extracts of the butterflies over a period of at least 6 hours. Labeled rinderine is efficiently N-oxidized and transformed into a metabolite of still unknown structure. These two metabolites are formed in almost equal amounts and account for more than 90% of total radioactivity. After four hours the toxic free base is only detectable in traces. Radioactively labeled senecioylretronecine (free base), a PA that often accompanies PAs of the lycopsamine type in plants, is metabolized in a different manner. The toxic free base disappeared as fast as the tertiary rinderine, but the final products which accumulated in a stable ratio after 12 hours were mainly two polar metabolites of unknown structure; senecioylretronecine N-oxide accounts for less than 10% of total PAs. Labeled senecionine a macrocyclic PA, which never has been found in wild caught M. polymnia is only slowly N-oxidized. In females ca 50% of the ingested senecionine is still present as free base after 24 hours, whereas under the same conditions in males this percentage is only ca 20%. This difference in N-oxidation was the only significant sex-specific difference observed in various experiments. Larvae of M. polymnia which feed on Solanum tabacifolium, a plant that does not contain PAs, are able to sequester and partly N-oxidize labeled senecioylretronecine and senecionine. However, the storage is not very efficient; with the two tracers less than 5% of radioactivity remained in the bodies after 24 hours.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1423-0445
    Keywords: pyrrolizidine alkaloid N-oxides ; alkaloid sequestration ; defensive secretion ; host plant ; Coleoptera ; Chrysomelidae ; Oreina ; Asteraceae ; Adenostyles alliariae ; Senecio fuchsii ; Petasites paradoxus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Oreina cacaliae andO. speciosissima (Coleoptera, Chrysomelidae) sequester in their elytral and pronotal defensive secretions pyrrolizidine alkaloids (PAs) as Noxides (PA N-oxides). The PA N-oxide patterns found in the beetles and their host plants were evaluated qualitatively and quantitatively by capillary gas chromatography/mass spectrometry (GC-MS). Of the three host plantsAdenostyles alliariae (Asteraceae) is the exclusive source for PA N-oxide sequestration in the defensive secretions of the beetles. With the exception of O-acetylseneciphylline the N-oxides of all PAs ofA. alliariae, i.e. senecionine, seneciphylline, spartioidine, integerrimine, platyphylline and neoplatyphylline were identified in the secretion. PA N-oxides typical ofSenecio fuchsii (Asteraceae) were detected in the bodies of the beetles but not in their secretion. No PAs were found in the leaves of the third host plant,Petasites paradoxus (Asteraceae). The results suggest the existence of two distinctive storage compartments for PA N-oxides in the beetle: (1) the defensive secretion, containing specifically PA N-oxides acquired fromA. alliariae; (2) the body of the beetle, sequestering additionally but less selectively PA N-oxides from other sources,e.g. S. fuchsii or monocrotaline N-oxide fed in the laboratory. The concentration of PA N-oxides in the defensive secretion is in the range of 0.1 to 0.3 mol/1, which is more than 2.5 orders of magnitude higher than that found in the body of the beetle. No significant differences exist in the ability of the two species of beetles to sequester PA N-oxides fromA. alliariae, althoughO. speciosissima, but notO. cacaliae, produces autogenous cardenolides. A negative correlation seems to exist between the concentrations of plant-derived PA N-oxides andde novo synthesized cardenolides in the defensive secretion ofO. speciosissima.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...