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  • 2005-2009
  • 1985-1989  (12)
  • 1945-1949
  • Biochemistry and Biotechnology  (12)
  • 1
    Electronic Resource
    Electronic Resource
    Peptide sequencing and site-directed mutagenesis identify tyrosine-319 as the active site tyrosine of Escherichia coli DNA topoisomerase I (1989)
    New York, NY : Wiley-Blackwell
    Proteins: Structure, Function, and Genetics 6 (1989), S. 231-239 
    Details
    ISSN: 0887-3585
    Keywords: phosphotyrosine linkage ; protein-DNA transesterification ; enzyme mechanism ; DNA-protein covalent complex ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Tyrosine 319 of E. coli topoisomerase I is shown to be the activesite tyrosine that becomes covalently attached to a DNA 5′ phosphoryl group during the transient breakage of a DNA internucleotide bond by the enzyme. The tyrosine was mapped by trapping the covalent complex between the DNA and DNA topoisomerase I, digesting the complex exhaustively with trypsin, and sequencing the DNA-linked tryptic peptide. Site-directed mutagenesis converting Tyr-319 to a serine or phenylalanine completely inactivates the enzyme. The structure of the enzyme andits catalysis of DNA strand breakage, passage, and rejoining are discussed in terms of the available information.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prot.340060305
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  • 2
    Electronic Resource
    Electronic Resource
    Agitation and pressure effects on acetone-butanol fermentation (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 852-860 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Batch fermentations were run at varying agitation rates and were either pressurized to 1 bar (15.2 psig) or nonpressurized. Agitation and pressure both affect the level of dissolved hydrogen gas in the media, which in turn influences solvent production. In nonpressurized fermentations volumetric productivity of butanol increased as the agitation rate decreased. While agitation had no significant effect on butanol productivity under pressurized conditions, overall butanol productivity was increased over that obtained in the nonpressurized runs. Maximum butyric acid productivity, however, was found to occur earlier and increased as agitation increased. Peak hydrogen productivity occurred simultaneously with peak butyric acid productivity. The proporation of reducing equivalents used in forming the above products was determined using a redox balance based on the fermentation stoichiometry. An inverse relationship between the final concentrations of acetone and acetoin was found in all fermentations studied. The results show that agitation and pressure are important parameters for solvent productivity in acetone-butanol fermentation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260270615
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Preservation of potential fermentables in sweet sorghum by ensiling (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 30 (1987), S. 860-867 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pressed and wilted samples of sweet sorghum [Sorghum bicolor (L.) Moench var. Rio] were ensiled for periods up to 155 days. A kinetic study of the biochemical changes which occurred during ensiling showed that in wilted sorghum ensilage invert sugars and mannitol levels collectively were maintained at 65% of the original ferment able sugar content of the sorghum. The acidic environment produced by ensiling also served as a pretreatment that resulted in enhanced yields of reducing sugar when the sorghum was contacted with cellulolytic enzymes. The quantity of sugar obtained from enzymatic hydrolysis more than compensated for carbohydrate used by organisms during the ensiling process. Both Saccharomyces uvarum and Clostridium acetobutylicum were able to ferment a medium constituted from pressed sorghum juice and the solution resulting from enzymatic hydrolysis of sweet sorghum ensilage.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260300708
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  • 4
    Electronic Resource
    Electronic Resource
    Characteristic reaction paths of biochemical reaction systems with time scale separation (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 847-854 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A technique has been developed for characterizing the in vivo behavior of key enzymes from intermediate measurements. The technique is based on the identification of characteristic reaction paths, and it depends on the time scale separation characteristics of the systems. It is shown that useful information can be obtained from the phase plots of properly selected intermediate pairs or combinations which typically show process insensitive algebraic relations approached on time scales short compared to those of most practical interest. These characteristic reaction paths provide useful global measures of enzyme activity. The mathematical basis of reaction path analysis is investigated using linear transformation techniques. General theorems are developed predicting the existence of characteristic reaction paths as asymptotic limits whenever there is effective time scale separation. These limits are reached when fast reactions are relaxed, and available evidence suggests that these conditions will occur for the majority of reaction networks.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260310813
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  • 5
    Electronic Resource
    Electronic Resource
    Lumping analysis of biochemical reaction systems with time scale separation (1988)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 869-879 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Due to the complexity of the systems, successful modelling of intracellular reaction networks must rely on lumping techniques which systematically reduce the number of variables and parameters. Fortunately, the time scale separation characteristics of biochemical systems provide opportunities for eliminating unnecessary details. Through the proper interpretation of eigenvalues and eigenvectors, this article presents a theoretical basis for systematic model reduction. Results are generalized as a semiheuristic basis for lumping systems without complete kinetic information. It is also illustrated that the simplified system can yield new insight which is otherwise unavailable.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260310815
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  • 6
    Electronic Resource
    Electronic Resource
    Dependence of in vivo inactivation kinetics of gramicidin S synthetase on cell physiology (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 1037-1044 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Gramicidin S synthetase, the enzyme complex catalyzing the biosynthesis of the antibiotic gramicidin S in Bacillus brevis, is subject to O2-dependent in vivo inactivation during exponential aerobic growth after reaching a peak in specific activity. The five amino acid substrates of the synthetase are capable of stabilizing its activity to varying degrees in whole cells shaken aerobically. Depending on the time of cell harvesting before, during, or after the peak in intracellular gramicidin S synthetase specific activity, the enzyme has a long, medium, or short half-life, respectively. The kinetic profiles of gramicidin S synthetase in B. brevis cells indicate that both the kinetics of synthetase loss and the degree of its amino-acid-mediated stabilization are a strong function of the cells' physiological development.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260340803
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  • 7
    Electronic Resource
    Electronic Resource
    Continuous hydrolysis of tallow with immobilized lipase in a microporous membrane (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1318-1322 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Thermostable lipase from Thermomyces lanuginosus was immobilized in untreated microporous membranes. Melted tallow pumped through the membrane did not wash the enzyme out. From 0.4 to 0.9% of the soluble activity remained after immobilization with half-lives of 1-2 months or more at 50°C. Membranes can be acid/base washed and reloaded with enzyme with no adverse effects. Buffer was required for a long half-life, and recycling the buffer improved the mass transfer of glycerol out of the immobilized lipase reactor. Immobilized activity was unaffected when the pH of the aqueous product changed from 5.5 to 6.5.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260280906
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  • 8
    Electronic Resource
    Electronic Resource
    Fermentation data analysis and state estimation in the presence of incomplete mass balance (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 613-622 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is developed for identifying measurement errors and estimating fermentation states in the presence of unidentified reactant or product. Unlike conventional approaches using elemental balances, this method employs an empirically determined basis, which can tolerate unidentified reaction species. The essence of this approach is derived from the concept of reaction subspace and the technique of singular value decomposition. It is shown that the subspace determined via singular value decomposition of multiple experimental data provides an empirical basis for identifying measurement errors. The same approach is applied to fermentation state estimation. Via the formulation of the reaction subspace, the sensitivity of state estimates to measurement errors is quantified in terms of a dimensionless quantity, maximum error gain (MEG). It is shown that using the empirically determined subspace, one can circumvent the problem of unidentified reaction species, meanwhile reducing the sensitivity of the estimates.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260330515
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of hydrogen acceptors on D-xylose fermentation by anaerobic culture of immobilized Pachysolen tannophilus cells (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 33 (1989), S. 839-844 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of hydrogen acceptors on the kinetic parameters of D-xylose fermentation under anaerobic conditions was studied in a transient culture of immobilized Pachysolen tannophilus cells. Addition of oxygen to a steady-state culture resulted in a rapid increase (up to fivefold) in the rates of ethanol production and D-xylose uptake, but the rate of xylitol production was unaffected. Furthermore, the molar ethanol yield increased from 0.97 to 1.43 in the presence of oxygen. The moles of ethanol produced per moles of oxygen utilized were considerably greater than would be predicted from the stoichiometry of D-xylose fermentation, which suggests that the organism required oxygen for other functions in addition to its role as a hydrogen acceptor in D-xylose metabolism. When the artificial hydrogen acceptors acetone, acetaldehyde, and acetoin were added to the culture, the rate of ethanol production increased while the xylitol production rate decreased but the rate of xylose uptake was unaffected. The molar ethanol yields increased from 1.03 to 1.63, 1.43, and 1.24 upon addition of acetaldehyde, acetone, and acetoin, respectively, at the expense of the molar xylitol yields. The hydrogen acceptors sodium acetate, methylene blue, benzyl viologen, phenazine methosulfate, indigo carmine, and tetrazolium chloride had no effect on ethanol production.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260330707
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  • 10
    Electronic Resource
    Electronic Resource
    Molecular recognition between oligopeptides and nucleic acids. Sequence specific binding of (4S)-(+)- and (4R)-(-)-dihydrokikumycin B to DNA deduced form 1H NMR, footprinting studies and thermodynamic data (1989)
    Chicester [u.a.] : Wiley-Blackwell
    Journal of Molecular Recognition 2 (1989), S. 6-17 
    Details
    ISSN: 0952-3499
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The sequence specific binding of the antibiotic (4S)-(+)-dihydrokikumycin B and its (4R)-(-)enantiomer, [(S)-I and (R)-I, respectively] to DNA were characterized by DNase I and MPE footprinting, calorimetry, UV, spectroscopy, circular dichroism, and 1H NMR studies. Footprinting analyses showed that both enantiomers [(S)-I and (R)-I] bind to AT-rich regions of DNA. 1H NMR studies (ligand induced chemical shift changes and NOE differences) of the dihydrokikumycins with d-[CGCAATTGCG]2 show unambiguously that the N to C termini of the ligands are bound to 5′-A5T6T7-3′ reading from left to right. From quantitative 1D-NOE studies, the AH2(5)-ligand H7 distance of complex A [(S)-I plus decamer (which is bound more strongely)] and complex B[(R)-I and decamer] are estimated to be 3.8 ± 0.3 Å and 4.9 ± 0.4 Å, respectively. This difference in binding properties is reflected in the thermodynamic profiles of the two enantiomeric ligands determined by a combination of spectroscopic and calorimetric techniques. The binding freee energies (ΔG°) of (S)-I and (R)-I to poly d(AT)·poly d(AT) at 25°C are -31.8 and -29.3 kJ mol-1, respectively while the corresponding binding enthalpies (ΔH°) are -11.3 and -0.8 kJ mol-1. These data permit the construction of models for the binding of the enantiomeric dihydrokikumycins to DNA and account for the more efficient binding of the natural (S) isomer to DNA.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmr.300020103
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