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  • Inorganic Chemistry  (8)
  • Acoustics  (7)
  • Biochemistry and Biotechnology  (7)
  • 1
    Electronic Resource
    Electronic Resource
    Expression of recombinant protein A from the lac promoter in Escherichia coli JM83 is not subject to catabolite repression when grown under specific conditions of continuous culture (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 1050-1058 
    Details
    ISSN: 0006-3592
    Keywords: catabolite repression ; protein A ; membrane proteins ; continuous culture ; protein expression ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Although widely used in experimental and industrial situations, genetically engineered plasmids containing the lac promoter from Escherichia coli are subject to catabolite repression when grown in glucose-containing media. Several methods of overcoming this problem have been investigated by studying the expression of the protein A gene from Staphylococcus aureus under the control of the Escherichia coli lac promoter. When glycerol is used as a sole carbon source, the plasmid is unstable and is rapidly lost from the culture. When the bacteria are grown in chemostats under glucose limitation, the plasmid is maintained, even at high dilution rates, and the expression of protein A is similar to that observed when glycerol was used. The balance between metabolic load and protein A expression seems to be maintained by reducing the gene dose to a tolerable level. Depending on the metabolic conditions prevailing in the culture, this is achieved, either by reducing the copy number of the plasmid or in extreme cases by removing the plasmid altogether.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380914
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  • 2
    Electronic Resource
    Electronic Resource
    The application of membrane biological reactors for the treatment of wastewaters (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 49 (1996), S. 601-610 
    Details
    ISSN: 0006-3592
    Keywords: aerobic ; anaerobic ; biomass separation ; bioreactor ; bubbleless ; oxygen mass transfer ; extraction of organic pollutants ; membrane ; wastewaters ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Combining membrane technology with biological reactors for the treatment of municipal and industrial wastewaters has led to the development of three generic membrane processes within bioreactors: for separation and recycle of solids; for bubbleless aeration of the bioreactor; and for extraction of priority organic pollutants from hostile industrial wastewaters. Commercial aerobic and anaerobic membrane separation bioreactors already provide a small footprint alternative to conventional biological treatment methods, producing a high-quality effluent at high organic loading rates. Both the bubbleless aeration and extractive membrane bioreactors are in the development stages. The former uses gas-permeable membranes to improve the mass transfer of oxygen to the bioreactor by providing bubbleless oxygen. By using a silicone membrane process, extractive membrane bioreactors transfer organic pollutants from chemically hostile wastewaters to a nutrient medium for subsequent biodegradation. All three membrane bioreactor (MBR) processes are comparatively and critically reviewed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Comparison of hydrolysis and esterification behavior of Humicola lanuginosa and Rhizomucor miehei lipases in AOT-stabilized water-in-oil microemulsions: II. Effect of temperature on reaction kinetics and general considerations of stability and productivity (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 190-196 
    Details
    ISSN: 0006-3592
    Keywords: hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RrnL), isolated from commercial preparations of Lipolase and Lipozyme, respectively, were solubilized in AOT-stabilized water-in-oil (w/o) microemulsions in n-heptane and aspects of their hydrolysis and condensation activity examined. The temperature dependence of HIL hydrolysis activity in unbuffered R = 10 microemulsions matched very closely that for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. Apparent activation energies were measured as 13 ± 2 and 15 ± 2 kJ mol / respectively. Condensation activity, however, was essentially independent of temperature over the range 5° to 37°C. The stability of HIL over a 30-day period was very good at all pH levels (6.1, 7.2, 9.3) and R values studied (5, 7.5, 10, 20), except when high pHs and low R values were combined. The excellent stability was reflected by the linearity of the productivity profiles which facilitate system optimization. The temperature dependence of RmL hydrolysis activity toward pNPC4 showed a maximum at 40°C and an apparent Eact = 20 ± 2 kJ mol-1 was calculated based on the linear region of the profile (5° to 40°C). RmL esterification activity showed only a slight dependence on temperature over the studied range (0° to 40°C) and an apparent Eact = 5 ± 1 kJ mol-1 was measured for octyl decanoate synthesis. Both RmL and HIL, therefore, have potential for application in low temperature biotransformations in microemulsion-based media. The stability of RmL over a 30-day period was good in R = 7.5 and R = 10 microemulsions containing pH 6.1 buffer, and this was reflected in the linearity of their respective productivity profiles. RmL stability was markedly poorer at more alkaline pH, however, and proved to be sensitive to relatively small changes in the R value. © 1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480304
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of hydrolysis and esterification behavior of Humicola lanuginosa and Rhizomucor miehei lipases in AOT-stabilized water-in-oil microemulsions: I. Effect of pH and water content on reaction kinetics (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 48 (1995), S. 78-88 
    Details
    ISSN: 0006-3592
    Keywords: hydrolysis ; esterification ; Humicola lanuginosa ; Rhizomucor miehei ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Lipolase and Lipozyme are produced in large quantities (as a result of genetic engineering and overexpression) for the detergents market and provide a cheap source of highly active biocatalysts. Humicola lanuginosa lipase (HIL) and Rhizomucor miehei lipase (RmL) have been isolated in partially purified form from commercial preparations of Lipolase and Lipozyme, respectively. These lipases were solubilized in Aerosol-OT (AOT)-stabilized water-in-oil (w/o) microemulsions in n-heptane. HIL and RmL activity in these microemulsions was assayed by spectrophotometric measurement of the initial rate of p-nitophenyl butyrate hydrolysis, and by chromatographic determination of the initial rate of octyl decanoate synthesis from 1-octanol and decanoic acid. The hydrolytic activity of HIL in microemulsions measured as a function of buffer pH prior to dispersal, followed a sigmoidal profile with the highest activities observed at alkaline pHs. This broadly matches the pH-activity profile for tributyrin hydrolysis by Lipolase in an aqueous emulsion assay. The hydrolytic activity of RmL in the same microemulsions, measured as a function of pH, gave a bell-shaped profile with a maximum activity at pH 7.5. Again, the observed pH-activity profile was similar to that reported for a purified RmL in a tributyrin-based aqueous emulsion assay. In contrast, the esterification activity exhibited by both HIL and RmL in AOT microemulsions over the available range pH 6.1 to 10.4, decreases as the pH increases, most likely reflecting the effect of substrate ionization. The dependence of the hydrolytic and condensation activity of HIL on R, the mole ratio of water to surfactant, were similar with both profiles exhibiting a maximum at R = 5. The hydrolytic and esterification activities of RmL followed similar R-dependent profiles, but the profiles in this case exhibited a maximum at R = 10. The water activities at these R values were directly measured as 0.78 and 0.9, respectively. Measured water activities were unperturbed by the presence of lipase at the concentrations used in these studies. © 1995 John Wiley & Sons, Inc.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260480111
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  • 5
    Electronic Resource
    Electronic Resource
    Darstellung und Eigenschaften von Tetrakis(trifluormethyl)-1,3-dithietan-S-oxiden und des Bis(trifluormethyl)sulfins (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 116-123 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Properties of Tetrakis(trifluoromethyl)-1,3-dithietane S-Oxides and Bis(triflouromethyl)sulfineThe corresponding S-oxides 2-6 could be obtained by oxidation of 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane (1). Similar oxidation of 2,2,4,4-tetrakis(trifluoromethyl)thiirane (8) yields the episulfoxide 12, but not the episulfone 14. Pyrolysis of 2, 3, 5, and 6 have been investigated and bis(trifluoromethyl)sulfine (7) could be isolated as the first member of perfluoroalkylsulfines as well as the sulfonylfluoride 13 being the product of isomerization of bis(trifluoromethyl)-sulfene (9). 7 could also be obtained by ring opening from 3 with bases and by oxidation of hexafluorothioacetone (11), respectively. Solvolytic ring opening in 5 and 6 yields the sulfones 16 and 17.
    Notes: Durch Oxidation des 2,2,4,4-Tetrakis(trifluormethyl)-1,3-dithietans (1) erhält man dessen S-Oxide 2-6. Auf gleiche Weise gelingt die Oxidation des 2,2,4,4-Tetrakis(trifluormethyl)thiirans (8) zum Episulfoxid 12, nicht jedoch zum Episulfon 14. Die Pyrolysen von 2, 3, 5 und 6 wurden untersucht, wobei als erster Vertreter der Perfluoralkylsulfine das Bis(trifluormethyl)sulfin (7) sowie das Sulfonylfluorid 13 als Isomerisierungsprodukt des Bis(trifluormethyl)sulfens (9) isoliert wurden. 7 entsteht auch durch Ringöffnung aus 3 mit Basen bzw. bei der Oxidation des Hexafluorthioacetons (11). Die Solvolyse von 5 und 6 liefert unter Ringöffnung die Sulfone 16 und 17.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180112
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  • 6
    Electronic Resource
    Electronic Resource
    Darstellung und Eigenschaften neuer perhalogenierter 1,3-Dithietan-S-oxide (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 1623-1630 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Synthesis and Properties of New Perhalogenated 1,3-Dithietane S-OxidesNew perchlorinated and perfluorinated 1,3-dithietanes (4, 6, 7, 12, 14, 15), which are partially oxidized at the sulfur atoms, are described. Pyrolysis of the 1,3-dioxides 7 and 15 leads to the sulfoxides 8 and 16, X2C = S = O (X = Cl, F). respectively. Two new oxidizing agents are used: trifluoromethane- and nonafluorobutanepersulfonic acid.
    Notes: Die neuen perchlorierten und perfluorierten, am Schwefel partiell oxidierten 1,3-Dithietane 4, 6, 7, 12, 14 und 15 werden beschrieben. Pyrolysen der 1,3-Dioxide 7 und 15 führen zu den Sulfoxiden 8 bzw. 16, X2C = S = O (X = Cl, F). Zwei neue Oxidationsmittel werden angewendet: Trifluormethan- und Nonafluorbutanpersulfonsäure.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831160437
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  • 7
    Electronic Resource
    Electronic Resource
    Sterisch überladene Cyclohexane, 3. 4,4,8,8,12,12-Hexamethyltrispiro[2.1.2.1.2.1]dodecan und 4,4,8,8,9,9,10,10-Octamethyldispiro[2.1.2.3]decan - Zwei per(cyclo)alkylierte Cyclohexane in Twistbootkonformation (1986)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 119 (1986), S. 1144-1161 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Sterically Crowded Cyclohexanes, 3. 4,4,8,8,12,12-Hexamethyltrispiro[2.1.2.1.2.1]dodecane and 4,4,8,8,9,9,10,10-Octamethyldispiro[2.1.2.3]decane - Two Per(cyclo)alkylated Cyclohexanes Adopting a Twistboat ConformationSynthesis, conformation, and dynamics of the title compounds 1 and 8 are described. 1 and [1-13C]-1 were obtained by sequential methylenation and cyclopropanation of 9. The hydrogenation of 1 yielded not only 7 and 8 but also 21 and 22. On the contrary, the hydrogenations of 15 and 19 yielded 16 and 20 exclusively. The conformation and dynamics of 1 followed from an analysis of the 13C DNMR spectra of [1-13C]-1, the conformation and dynamics of 8 from an analysis of the 1H and 13C DNMR spectra of unlabelled material. Both compounds adopt a twistboat conformation. The activation parameters of the twistboat-to-twistboat interconversion of 1 were determined by bandshape analysis, those of 8 by the coalescence method. The results were as follows: 1: ΔH≠ = 8.5 · 0.2 kcal/mol, ΔS≠ = 12.8 ± 1.5 cal/mol · grd, ΔG298≠ = 4.7 ± 0.2 kcal/mol; 8: ΔG300≠ 13.6 kcal/mol. The unusual conformations of 1 and 8 are discussed on the basis of nonbonding interactions.
    Notes: Synthese, Konformation und Dynamik der Titelverbindungen 1 und 8 werden beschrieben. 1 und [1-13C]-1 wurden durch Methylenierung und anschließende Cyclopropanierung von 9 erhalten. Die Hydrierung von 1 lieferte neben 7 und 8 auch 21 und 22. Die Hydrierungen von 15 und 19 lieferten dagegen ausschließlich 16 bzw. 20. Die Konformation und Dynamik von 1 ergab sich aus einer Analyse der 13C-DNMR-Spektren von [1-13C]-1, die Konformation und Dynamik von 8 aus einer Analyse der aH- und 13C-DNMR-Spektren unmarkierten Materials. Beide Verbindungen liegen in einer Twistbootkonformation vor. Die Aktivierungsparameter der Twistboot-Twistboot-Inversion wurden bei 1 über eine Bandenformanalyse, bei 8 nach der Koaleszenztemperaturmethode bestimmt. Danach ergaben sich folgende Werte: 1: ΔH≠ = 8.5 ± 0.2 kcal/mol, ΔS≠ = 12.8 ± 1.5 cal/mol · grd, ΔG298≠ = 4.7 ± 0.2 kcal/mol; 8: ΔG300≠ = 13.6 kcal/mol. Die ungewöhnlichen Konformationen von 1 und 8 werden auf der Grundlage nichtbindender Wechselwirkungen diskutiert.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19861190406
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  • 8
    Electronic Resource
    Electronic Resource
    (E, Z)1-Equilibria, 17 Demonstration of the Nitrogen Inversion Mechanism of Imines in a Schiff Base ModelDedicated to Professor Heinrich Nöth on the occasion of his 65th birthday. (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 747-754 
    Details
    ISSN: 0009-2940
    Keywords: Diastereotopomerization, (E, Z) ; Imines ; Inversion, nitrogen ; Permethylation ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experimental differentiation between pure C=N double bond rotation and nitrogen inversion in N1-arylimines is possible with a single compound (13b) under the proviso of slow rotation about the N-aryl single bond. Labelling by 1H and 13C nuclei at the diastereotopic faces of the C=N moiety as well as of the N-aryl group is the clue to a successful stereodynamic analysis, as performed by variable-temperature NMR spectroscopy of 13b, a sterically congested and chiral model compound. Interpretation of similar measurements on a second model (13d) is less straightforward. The experimental observation of time-averaged Cs symmetry by NMR coalescences is only compatible with a mechanism of (E/Z) stereomutation either by pure inversion at sp2 nitrogen or by a contribution from C=N rotation together with a synchronized (geared) controtation about the N-aryl single bond. However, the latter combination is concluded to be predominantly inversion-like by comparisons with related imines.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19931260327
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  • 9
    Electronic Resource
    Electronic Resource
    (E,Z) Equilibria, 14. Substituent-Induced Chemical Shifts along the C = N Bond of Schiff Bases (1992)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 125 (1992), S. 2033-2040 
    Details
    ISSN: 0009-2940
    Keywords: 13C NMR, SCS ; Substituent effects ; Imines ; Isomerization, (E,Z) Schiff bases ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Sterically congested N-(1,1,3,3-tetraalkyl-2-indanylidene)-amines 8-11, N-(cyclopentylidene)anilines 13-17, and two of their salts are described, together with a short synthesis of 2-imino-1,1,3,3-tetramethylindan (5). Some of these imines show rapid (E,Z) equilibration. Positively and negatively charged nitrogen functions (in 6 and 7) cause opposite 1H- and 13C-NMR chemical shift effects along the C = N bond. Chemical shifts are almost equally affected by the lone electron pair and by the imino N-H bond. Substituent-induced chemical shifts (SCS) have been assigned for all syn and anti positions with respect to methyl, phenyl, and 2,6-dimethylphenyl groups at the imino nitrogen atom. The structurally well-defined, rigid imines recommend themselves as new models for the calibration of theoretical approaches to syn/anti-differentiating SCS.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19921250911
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  • 10
    Electronic Resource
    Electronic Resource
    Proline excretion by Escherichia coli K12A preliminary report of this research was made at the Fourth International Symposium on the Genetics of Industrial Microoganisms in Kyoto, Japan, June, 1982. (1984)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 74-80 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Proline excretion from proline overproducing strains of E. coli K12 has been studied as a model chemical production system. We have isolated proline overproducing mutants of E. coli and have shown that uncontrolled synthesis is not sufficient to cause excretion of this amino acid. An episomal mutation causing proline over production has been introduced into a series of otherwise isogenic strains that bear well defined, chromosomal lesions affecting the active uptake and catabolism of L-proline. A syntropism test reveals that L-proline is excreted by overproducing strains only if transport and/or catabolism are impaired. Dansyl derivatization and chromatographic analysis of culture supernatants shows that proline is the only amino acid excreted. Batch cultures of an excreting strain in an amino acid production medium yield culture supernatants containing 1 g proline/L, whereas no proline is detectable in supernatants derived from cultures of an overproducing strain with normal transport and catabolic activities. These data reveal that genetic lesions eliminating active uptake can be used to specifically enhance metabolite excretion.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260260114
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