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  • 1
    Electronic Resource
    Electronic Resource
    A novel technique for the measurement of disruption in high-pressure homogenization: Studies on E. coli containing recombinant inclusion bodies (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 363-370 
    Details
    ISSN: 0006-3592
    Keywords: homogenization, high-pressure ; cell disruption ; inclusion bodies ; size distribution ; centrifuge, analytical ; Escherichia coli ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The high-pressure homogenization of Escherichia coli, strain JM101, containing inclusion bodies of recombinant porcine somatotropin was investigated. A novel technique employing an analytical disc centrifuge was used to monitor the disruption. This a direct technique which measures cell disintegration rather than soluble protein release. The technique is particularly suited to measurements where the disruption approaches 100%. The disk centrifuge provides a size distribution of the homogenate, and furnishes evidence for the preferential disruption of larger cells. For E. coli containing inclusion bodies, and increase in the cell feed concentration from 145 g/L (wet weight) to 330 g/L resulted is poorer homogenization. Poorer disruption was also obtained by lowering the feed temperature from 20°C to 5°C. Only slight variations in performance were obtained by increasing the feed pH from 7.5 to 9.0 or by storing the feed at 4°C for 24 h prior to disruption. Comparison with uninduced E. coli strain JM101, showed that the disruption obtained is higher for bacteria containing a recombinant inclusion body.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260380406
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Numerical and experimental study of a homogenizer impinging jet (1997)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 1100-1107 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: High-pressure homogenization is a key unit operation used to disrupt cells containing intracellular bioproducts. Modeling and optimization of this unit are restrained by a lack of information on the flow conditions within a homogenizer valve. A numerical investigation of the impinging radial jet within a homogenizer valve is presented. Results for a laminar and turbulent (k - ∊ turbulent model) jet are obtained using the PHOENICS finite-volume code. Experimental measurement of the stagnation region width and correlation of the cell disruption efficiency with jet stagnation pressure both indicate that the impinging jet in the homogenizer system examined is likely to be laminar under normal operating conditions. Correlation of disruption data with laminar stagnation pressure provides a better description of experimental variability than existing correlations using total pressure drop or the grouping 1/Y2h2.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690430423
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Design analysis for refolding monomeric protein (1997)
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 43 (1997), S. 2123-2132 
    Details
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Renaturation of protein expressed as inclusion bodies within Escherichia coli is a key step in many bioprocesses. Operating conditions for the refolding step dramatically affect the amount of protein product recoverd, and hence profoundly influence the process economics. The first systematic comparison of refolding conducted in batch, fed-batch and continuous stirred-tank reactors is provided. Refolding is modeled as kinetic competition between first-order refolding (equilibrium reaction) and irreversible aggregation (second-order). Simulations presented allow direct comparison between different flowsheets and refolding schemes using a dimensionless economic objective. As expected from examination of the reaction kinetics, batch operation is the most inefficient mode. For the base process considered, the overall cost of fed-batch and continuous refolding is virtually identical (less than half than of the batch process). Reactor selection and optimization of refolding using overall economics are demonstrated to be vitally important.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/aic.690430819
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical treatment of Escherichia coli: 1. Extraction of intracellular protein from uninduced cells (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 53 (1997), S. 453-458 
    Details
    ISSN: 0006-3592
    Keywords: chemical permeabilization ; cell disruption ; urea ; EDTA ; Escherichia coli ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Extraction of intracellular protein from Escherichia coli is traditionally achieved by mechanical disruption. A chemical treatment that destroys the integrity of the bacterial cell wall and could provide an alternative technique is examined in this study. Treatment with a combination of the chelating agent ethylenediaminetet-raacetate (EDTA) (greater than 0.3 mM) and the chaotropic agent urea (6 M) is highly effective at releasing protein from uninduced E. coli. The 6 M urea in the presence of 3 mM EDTA can release cytoplasmic protein from both logarithmic-phase and stationary-phase E. coli cells at levels equivalent to mechanical disruption. The concentrations of the two chemical agents were the major variables affecting the maximum levels of protein release. Several minor variables and interactions were also identified. The kinetics of protein release is first order. For 2, 4, and 6 M urea with 3 mM EDTA, the time constant is approximately 2.5 min independent of urea concentration. Kinetics for 3 mM EDTA without urea is considerably slower, with a time constant of 12.3 min. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 53: 453-458, 1997.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Chemical treatment of Escherichia coli. II. Direct extraction of recombinant protein from cytoplasmic inclusion bodies in intact cells (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 57 (1998), S. 381-386 
    Details
    ISSN: 0006-3592
    Keywords: inclusion bodies ; recombinant protein ; IGF-I ; urea ; Escherichia coli ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method is presented for the direct extraction of the recombinant protein Long-R3-IGF-I from inclusion bodies located in the cytoplasm of intact Escherichia coli cells. Chemical treatment with 6M urea, 3 mM EDTA, and 20 mM dithiothreitol (DTT) at pH 9.0 proved an effective combination for extracting recombinant protein from intact cells. Comparable levels of Long-R3-IGF-I were recovered by direct extraction as achieved by in vitro dissolution following mechanical disruption. However, the purity of directly extracted recombinant protein was lower due to contamination by bacterial cell components. The kinetics of direct extraction are described using a first-order equation with the time constant of 3 min. Urea appears important for permeabilization of the cell and dissolution of the inclusion body. Conversely, EDTA is involved in permeabilization of the cell wall and DTT enhances protein release. pH proved to be important with lower levels of protein release achieved at low pH values (〈9). Cell concentration also had a minor effect on Long-R3-IGF-I release and caused an observable increase in viscosity. Advantages of the direct extraction method include its speed, simplicity, and efficiency at releasing product. ©1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57:381-386, 1998.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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