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  • 1
    Call number: AWI G6-22-94889
    Type of Medium: Monograph available for loan
    Pages: XII, 430 Seiten , Illustrationen , 24 cm
    ISBN: 3-540-06587-3 , 0-387-06587-3
    Series Statement: Anwendung von Isotopen in der organischen Chemie und Biochemie Band 2
    Language: German
    Note: Inhaltsverzeichnis Vorwort Adressenliste der Autoren A. Einleitung / H. SIMON und P. RAUSCHENBACH 1. Begriffe und Definitionen 1.1. Absorption, Ionisation, Anregung und Bremsstrahlung von β-Strahlung 1.2. γ- und Röntgen-Strahlung, Mechanismen der Absorption 1.3. Häufig verwendete radioaktive Isotope 1.4. Literatur und Bibliographie B. Allgemeines und Prinzipien der Radioaktivitätsmessung / H. SIMON und P. RAUSCHENBACH 1. Absolut- und Relativmessung von Radioaktivität 2. Ionisationskammern und Zählrohre 2.1. Ionisationskammern 2.2. Zählrohre 2.2.1. Zählrohre zur Messung von β-Strahlung 2.2.2. Zählrohre zur Messung von γ-Strahlung 3. Halbleiterdetektoren / R. TYKVA 4. Szintillationszähler 4.1. Allgemeines über Szintillationszähler 4.2. Messung mit flüssigen Szintillatoren 4.2.1. Lösungsmittel 4.2.2. Probengefäße 4.2.3. Szintillator-Substanzen 4.2.4. Löscheffekte, Phosphoreszenz und Chemolumineszenz 4.3. Messung durch Čerenkov-Strahlung 4.4. Messung von γ-Strahlern mit festen Szintillatoren 4.4.1. Impulshöhenverteilung, γ-Spektroskopie und Auflösungsvermögen 4.4.2. Einfluß verschiedener Parameter auf die Gestalt des Spektrums 5. Literatur C. Parameter, die auf Genauigkeit und Reproduzierbarkeit von Einfluß sind. Fehlerbetrachtung / P. RAUSCHENBACH 1. Der radioaktive Zerfall als statistischer Vorgang 2. Einfluß von Probenaktivität, Nulleffekt und Meßzeit auf den Fehler der Nettozählrate 2.1. Meßzeitoptimierung 3. Grenzempfindlichkeit und Gütezahl 4. Fehler von Ratemeter-Messungen 5. Ermittlung von Störeffekten an Meßanordnungen aufgrund nichtstatistischer Ergebnisse 6. Erkennung eines zu hohen Fehlers einer Einzelmessung 7. Literatur D. Präparation der Proben und deren Messung / P. RAUSCHENBACH und H. SIMON 1. Messung in fester oder flüssiger Form mit Zählrohren 1.1. T-, 14C-, 35S- und 45Ca-markierte Proben 2. Messung in der Gasphase nach Proben-Umwandlung 2.1. Tritium-markierte Proben 2.2. 14C- und T / 14C-doppelmarkierte Substanzen 2.3. Literatur 3. Flüssig-Szintillations-Messung 3.1. Probenpräparation 3.1.1. Direkt-Messung (ohne Probenumwandlung) 3.1.1.1. Homogene Meßsysteme 3.1.1.1.1. Messung ohne Lösungsvermittler 3.1.1.1.2. Messung mit Lösungsvermittlern 3.1.1.1.3. Messung von Wasser und wäßrigen Lösungen 3.1.1.1.4. Häufig verwendete Szintillatorsysteme 3.1.1.2. Heterogene Meßsysteme 3.1.1.2.1. Emulsionen 3.1.1.2.2. Suspensionen 3.1.1.2.3. Andere heterogene Materialien wie Papierstreifen, Dünnschicht- und Glasfaserproben 3.1.1.2.4. Häufig verwendete Szintillatorsysteme 3.1.2. Messung nach Probenumwandlung 3.1.2.1. Absorption gasförmiger Proben 3.1.2.2. Umwandlung in flüssiger Phase 3.1.2.2.1. Solubilisierung 3.1.2.2.2. Naß-Oxidation 3.1.2.3. Trockene Oxidation 3.1.2.3.1. Sauerstoff-Kolben-Verfahren 3.1.2.3.2. Sauerstoff-Strom-Verfahren 3.1.2.3.3. Oxidation im Bombenrohr oder in der Metallbombe 3.1.2.4. Spezielle Umwandlungsverfahren 3.2. Bestimmung der Zählausbeute (Löschkorrektur) 3.2.1. Interne Standardisierung 3.2.2. Löschkorrektur-Verfahren, aufgrund der Verschiebung des Proben-Impuls-Spektrums 3.2.2.1. Löschkompensation 3.2.2.2. Proben-Kanalverhältnis-Methode 3.2.2.3. Verstärkungsverhältnis-Methode 3.2.3. Externe Standardisierung 3.2.3.1. Verfahren basierend auf der Zählrate des externen Standards 3.2.3.1.1. Standard im Zählfläschchen angeordnet 3.2.3.1.2. Standard außerhalb des Zählfläschchens angeordnet 3.2.3.2. Externe Standard-Kanalverhältnis-Methode 3.2.3.2.1. Rechnerische Weiterverarbeitung der Meßwerte 3.2.4. Nachverstärkungs-Methode 3.2.5. Koinzidenz-Methoden 3.2.6. Verdünnungs-Methode 3.3. Datenverarbeitung 3.4. Literatur E. Die Bestimmung geringer Radioaktivität / R. TYKVA 1. Fragestellungen, welche die Bestimmung geringer Radioaktivität erfordern 2. Wahl der Bestimmungsmethode 3. Allgemeine Gesichtspunkte für ein Laboratorium zur Messung geringer Radioaktivität 3.1. Lokalisierung und Ausstattung 3.1.1. Konstruktionsmaterialien 3.1.2. Elektrische Entstörung der Meßeinrichtung 3.2. Erhöhung der Bestimmungsempfindlichkeit 3.2.1. Erniedrigung des Nulleffektes durch mechanische Abschirmung, Antikoinzidenz- oder Koinzidenzschaltung, Impulshöhen- und Anstiegszeitdiskrimination 3.2.2. Erhöhung der spezifischen Radioaktivität vor der Messung 4. Die einzelnen Meßverfahren 5. Literatur. F. Messung mehrfachmarkierter Proben / R. TYKVA 1. Beispiele für die Verwendung und das Vorkommen mehrerer Radionuklide in einem Versuchssystem 2. Prinzipien der Meßverfahren 2.1. Flüssig-Szintillations-Zählung 2.1.1. Messung nach vorangehender Trennung der Radionuklide 2.1.2. Gleichzeitige Messung aufgrund unterschiedlicher Impulshöhenspektren 2.1.2.1. Prinzip der Methode 2.1.2.2. Berechnung der Zerfallsraten der einzelnen Nuklide von doppelmarkierten Proben 2.1.2.3. Die Wahl optimaler Arbeitsbedingungen bei der Messung löslicher, wenig gelöschter Proben 2.1.2.4. Bestimmung unlöslicher oder stark gelöschter Proben 2.2. Ionisationsmethoden und Halbleiterdetektoren 3. Literatur G. Radiochromatographie / M. WENZEL 1. Einleitung 2. Papier- und Dünnschicht-Chromatographie 2.1. Allgemeine Aspekte 2.2. Direktmessung von Chromatogrammen und Elektropherogrammen 2.2.1. Papier-Chromatogramme und Elektropherogramme 2.2.2. Dünnschicht-Chromatogramme 2.2.3. Direktmessung von Parallel- und zweidimensionalen Chromatogrammen 2.2.4. Messung von doppelt-markierten Chromatogrammen 2.2.5. Zählausbeute und weitere Meßparameter bei der Direktmessung 2.2.6. Kombination verschiedener Parameter 2.3. Diskontinuierliche Messung von Chromatogrammen 2.3.1. Diskontinuierliche Messung von Papier- und Dünnschicht-Chromatogrammen 2.4. Autoradiographische Verfahren 2.4.1. Film-Autoradiographie 2.4.2. Autoradiographie mit der Funkenkammer 3. Auswertung von Gel-Elektropherogrammen 4. Säulen-Chromatographie mit radioaktiven Lösungen 4.1. Kontinuierliche Messung 4.1.1. Durchfluß-Zellen aus Szintillator-Schläuchen 4.1.2. Durchfluß-Zellen mit fester Szintillator-Füllung 4.1.3. Durchfluß-Zellen für homogene Systeme 4.1.4. Radioaktivitäts-Messung von Eluaten durch Čerenkov-Strahlung 4.2. Diskontinuierliche Messung 5. Radio-Gaschromatographie / H. SIMON 5.1. Einleitung 5.2. Einfluß verschiedener Parameter aufionisations-Detektoren 5.3. Apparatur und Arbeitsweise für hydrierende Crackung bzw. Oxidation 5.4. Grenzempfindlichkeiten 6. Verschiedene der Radiochromatographie verwandte Meßmethoden 6.1. Messung radioaktiver Zellsuspensionen auf Filtrierpapier 6.2. Messung radioaktiver Gewebe-Schnitte 6.3. In vivo Scanning bei Kleintieren (»Szintigraphie«) 7. Registriermöglichkeiten 7.1. Digitale und analoge Darstellung der Aktivitätsverteilung 7.2. Elektronische Peak-Integration 7.3. Darstellung der Aktivitätsverteilung und Peak-Integration mit einem Vielkanal-Analysator 8. Beispiele für Anwendung der Radiochromatographie zur Reinheitskontrolle radioaktiver Substanzen 8.1. Reinheitskontrolle von 131J-Hippuran und 131J-Thyroxin 8.2. Reinheitskontrolle bzw. Reinigung von (6, 7-T)-Östradiol 9. Literatur H. Analyse von stabil-isotop markierten Verbindungen / H.-L. SCHMIDT 1. Anwendungen stabiler Isotope und Grundlagen ihrer Analytik 2. Elementaranalytische Isotopen-Bestimmungen 2.1. Verfahren zum Aufschluß von markierten Verbindungen 2.1.1. Aufarbeitung von Proben zur Deuterium-Analyse 2.1.1.1. Verbrennung Deuterium-haltiger organischer Verbindungen und Isolierung des Wassers 2.1.1.2. Verbrennung organischer Substanzen und Reduktion von Wasser für die massenspektrometrische Deuterium-Analyse 2.1.1.3. Einstufen-Verfahren zur Gewinnung von Wasserstoff und automatisierte Wasser-Reduktion 2.1.1.4. Bestimmung von Deuterium in acidem Wasserstoff 2.1.2. Aufbereitung von Proben zur 13C-Analyse 2.1.2.1. Verbrennung von Kohlenstoff-haltigem Material nach dem Prinzip der organischen Elementaranalyse 2.1.2.2. Probenbereitung aus anorganischem Material und aus Wässern 2.1.3. Probenchemie zur 15N-Analyse 2.1.3.1. Kjeldahl-Aufschluß und Hypobromit-Oxidation 2.1.3.2. Ox
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  • 2
    Monograph available for loan
    Monograph available for loan
    Stuttgart : Boorberg
    Call number: PIK C 111-95-0172
    Type of Medium: Monograph available for loan
    Pages: xiv, 370 S.
    ISBN: 3415019934
    Branch Library: PIK Library
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 17 (1969), S. 1017-1020 
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 34 (1962), S. 1753-1755 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-072X
    Keywords: 3-Oxobutyryl-CoA reductase ; Ethyl (S)-3-hydroxybutyrate ; Clostridium tyrobutyricum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract An NADH-dependent (S)-specific 3-oxobutyryl-CoA reductase from Clostridium tyrobutyricum was purified 15-fold with a yield of 46%. It was homogeneous by gel electrophoresis after three chromatographic steps. The apparent molecular mass was estimated by column chromatography to be 240 kDa. SDS-gel electrophoresis revealed the presence of 33 kDa subunits. Substrates of the enzyme were ethyl and methyl 3-oxobutyrate, 3-oxobutyryl-N-acetylcysteamine thioester, and 3-oxobutyryl coenzyme A. The specific activities were 340 and 10 U (mg protein)-1 for the reduction of 3-oxobutyryl coenzyme A and ethyl 3-oxobutyrate, respectively; the Michaelis constants were 300 μM and 300 mM, respectively. The identity of 12 N-terminal amino acid residues was determined. The ezmyme was used in a preparative reduction of substrate, yielding ethyl (S)-3-hydroxybutyrate (〉99% enantiomeric excess).
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  • 6
    ISSN: 1432-072X
    Keywords: Amino acid fermentation ; Clostridia ; Enoate reductase ; 2-Oxo-carboxylate reductase ; Peptostreptococcus anaerobius ; Stickland reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Enoate reductase present in Clostridium kluyveri and Clostridium spec. La 1 could be detected in three strains of C. tyrobutyricum and ten clostridia belonging to the groups of proteolytic and saccharolytic or proteolytic species, respectively. In C. pasteurianum, C. butyricum and C. propionicum enoate reductase could not be found even after growth on (E)-2-butenoate. A 2-oxo-carboxylate reductase was present in rather low activities in the non-proteolytic clostridia which produce enoate reductase. High activities (up to 10 U/mg protein) of 2-oxo-carboxylate reductase were found in six of ten proteolytic clostridia. The substrate specificies of the enoate reductase and the 2-oxocarboxylate reductases from the proteolytic clostridia were determined with different α,β-unsaturated carboxylates (enoates) and 2-oxo-carboxylates, respectively. Enoates as well as 2-oxo-carboxylates are intermediates of the pathway by which amino acids are degraded. An explanation is offered for the long known but not understood fact that in the Stickland reaction isoleucine always acts as an electron donor and leucine and phenylalanine can be electron acceptors as well as donors. Peptostreptococus anaerobius converting some amino acids to the same products as C. sporogenes did this also with the intermediates which were found for the reductive deamination of amino acids in C. sporogenes, however, in crude extracts reduction of enoates occurred only in an activated form.
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  • 7
    ISSN: 1432-072X
    Keywords: Clostridium sp. La 1 ; Carbon sources ; Clostridium kluyveri ; Hydrogenase ; Enoate reductase ; Relationship of enoate reductase and hydrogenase ; Iron ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The enzyme activities of Clostridium La 1 and Clostridium kluyveri involved in the stereospecific hydrogenation of α,β-unsaturated carbonyl compounds with hydrogen gas were measured. In C. La 1 the specific activities of hydrogenase and enoate reductase depended heavily on the growth phase and the composition of the medium. During growth in batch cultures on 70 mM crotonate the specific activity of hydrogenase increased and then dropped to about 10% of its maximum value, whereas the activity of enoate reductase reached its maximum in cells of the stationary phase. Under certain conditions during growth the activity ratio hydrogenase: enoate reductase changed from 120 to 1. Thus, the rate limiting enzyme for the hydrogenation can be either the hydrogenase or the enoate reductase, depending on the growth conditions of the cells. The specific activities of ferredoxin-NAD reductase and butyryl-CoA dehydrogenase increased 3-4-fold during growth on crotonate. By turbidostatic experiments it was shown that at constant input of high crotonate concentrations (200 mM) the enoate reductase activity was almost completely suppressed; it increased steadily with decreasing crotonate down to an input concentration of 35 mM. Glucose as carbon source led to high hydrogenase and negligible enoate reductase activities. The latter could be induced by changing the carbon source of the medium from glucose to crotonate. Tetracycline inhibited the formation of enoate reductase. A series of other carbon sources was tested. They can be divided into ones which result in high hydrogenase and rather low enoate reductase activities and others which cause the reverse effect. When the Fe2+ concentration in crotonate medium was growth limiting, cells with relatively high hydrogenase activity and very low enoate reductase activity in the stationary phase were obtained. At Fe2+ concentrations above 3·10-7 M enoate reductase increased and hydrogenase activity reached its minimum. The ratio of activities changes by a factor of about 200. In a similar way the dependence of enzyme activities on the concentration of sulfate was studied. In batch cultures of Clostridium kluyveri a similar opposite time course of enoate reductase and hydrogenase was found. The possible physiological significance of this behavior is discussed.
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  • 8
    ISSN: 1432-072X
    Keywords: Aldehyde oxidoreductase ; Clostridium formicoaceticum ; Molybdenum containing ; Substrate specificity ; Tungsten-containing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clostridium formicoaceticum grown in the presence of 1 mM molybdate and about 1.5×10-5 mM tungsten (present in the 5 g yeast extract/l of the growth medium) forms two reversible aldehyde oxidoreductases in an activity ratio of about 45:55. The fraction of 45% does not bind to the octyl-Sepharose column, whereas the 55% aldehyde oxidoreductase binds to this column. From cells grown on a synthetic medium without the addition of tungstate only about 2% of the aldehyde oxidoreductase of the crude extract binds to octyl-Sepharose. The enzyme not binding to octyl-Sepharose has been purified as judged by electrophoresis. It is pure after about 50 fold enrichment. According to SDS gel electrophoresis the enzyme consists of identical 100 kD subunits. Based on gel chromatography it seems to be a trimer. Per subunit 0.6 molybdenum, 7 iron, 6.6 acid labile sulphur, about 0.1 pterin-6-carboxylic and 〈0.05 tungsten have been found. The first 13 amino acids from the amino end show no similarity with the W-containing aldehyde oxidoreductase from the same bacterium. With reduced tetramethylviologen (E0=−550 mV) the new molybdenum containing enzyme can reduce various aliphatic and aromatic acids to aldehydes. The pH optimum is at 6.0. For the dehydrogenation of butyraldehyde a rather broad pH region from pH 6 to 10 shows almost no variation of rate. From 15 different aldehydes acetaldehyde exhibits the highest rate. The Km value for butanal is 0.002 and for propionate 7.0 mM. Compared with the tungsten enzyme the molybdenum enzyme is only moderately oxygen-sensitive.
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  • 9
    ISSN: 1432-072X
    Keywords: Clostridium kluyveri ; Crotonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Clostridium La 1 obtained from a Clostridium kluyveri culture was compared with a typical C. kluyvery strain (DSM 555). The former grows on crotonate and is unable to use ethanol-acetate as carbon sources. The latter grows on crotonate only after long adaptation periods. Resting cells of both strains show also pronounced differences in the fermentation of crotonate. This holds even for C. kluyveri grown on crotonate. Besides several other differences the most striking is that there is no hybridization between the DNA of both strains. Crotonate seems not to be a very special carbon source since C. butyricum and C. pasteurianum grow on crotonate medium supplemented by peptone and yeast extract.
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  • 10
    ISSN: 1432-072X
    Keywords: Acylate reduction ; Clostridium formicoaceticum ; Carbon monoxide ; Formate ; Artificial mediators ; Viologens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Crude extracts or supernatants of broken cells of Clostridium formicoaceticum reduce unbranched, branched, saturated and unsaturated carboxylates at the expense of carbon monoxide to the corresponding alcohols. The presence of viologens with redox potentials varying from E 0′=-295 to-650 mV decreased the rate of propionate reduction. The more the propionate reduction was diminished the more formate was formed from carbon monoxide. The lowest propionate reduction and highest formate formation was observed with methylviologen. The carbon-carbon double bond of E-2-methyl-butenoate was only hydrogenated when a viologen was present. Formate as electron donor led only in the presence of viologens to the formation of propanol from propionate. The reduction of propionate at the expense of a reduced viologen can be followed in cuvettes. With respect to propionate Michaelis Menten behavior was observed. Experiments are described which lead to the assumption that the carboxylates are reduced in a non-activated form. That would be new type of biological reduction.
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