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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 491-497 
    ISSN: 0006-3592
    Keywords: membrane ; microfiltration ; enzyme ; activity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study of the interaction of the enzyme yeast alcohol dehydrogenase (YADH) with microfiltration membranes has been carried out. Most measurements were made with capillary pore inorganic membranes (Anopore) with some comparative measurements being made with polymeric membranes of low protein affinity (Durapore). It has been shown that the prolonged exposure of the enzyme to the inorganic membrane under low-shear conditions (slow recycle) resulted in a loss of enzyme activity. Under filtration conditions, the membrane permeation rate decreased continuously with time. This decrease could be quantified using the standard blocking filtration law, which describes a decrease in pore volume due to deposition of enzyme on the walls of the pore. No significant loss in activity of permeating enzyme occurred under solution conditions where the enzyme was stable. However, a significant loss of such activity occurred under solution conditions where the enzyme was slightly unstable. The experiments indicate that the likely mechanism for activity loss is a membrane/enzyme interaction resulting from a shear induced deformation of the enzyme structure. Two conclusions of practical importance are drawn from the work. © 1992 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 28-35 
    ISSN: 0006-3592
    Keywords: microfiltration ; membrane ; enzyme ; fouling ; atomic force microscopy ; photon correlation spectroscopy ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The transmission and rate of filtration of the enzyme yeast alcohol dehydrogenase (YADH) has been studied at capillary pore microfiltration membranes. Photon correlation spectroscopy (PCS) with nanometer resolution showed that the enzyme existed as discreate molecules only for a narrow range of pH and ionic strength. Under such conditions, the transmission of the enzyme was high. However, the rate of filtration still decreased continuously with time. Analyssis of the time dependence of the rate of filtration indicated that this decrease was due to in-pore enzyme deposition at low concentration (“standard blocking model”) and suface depositon at high concentration (“cake filtration model”). Use of atomic force microscopy (AFM) gave unequivocal and quantitative confirmation of these inferences. The work shows the great advantage of using advanced physical characterization techniques, both for the identification of the optimum conditions for filtration (PCS) and for the elucidation of mechanisms giving rise to inefficiencies in the filtration process (AFM). © 1995 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 38 (1991), S. 688-696 
    ISSN: 0006-3592
    Keywords: microfiltration ; protein filtration ; membrane fouling ; standard blocking filtration law ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: An experimental study of permeation of dilute BSA solutions (filtration) at microfiltration membranes has been carried out. Most measurements were made with capillary pore aluminum oxide membranes, with some comparative measurements with tortuous and capillary pore polymeric membranes. In all cases, a continuous and substantial decrease in the rate of permeation with time was observed. This decrease in permeation with time was observed. This decrease in permeation rate was due neither to concentration polarization nor to protein adsorption alone. However, it could be quantified using the standard blocking filtration law, which describes a decrease in pore volume due to deposition of protein on the walls of the pore. The maximum calculated thickness of the deposited layers was 55nm on the walls of 200-nm diameter pores. This phenomenon is quite different to adsorption of protein at such surfaces, this latter giving only sub-monolayer or monolayer protein coverage under the conditions studied.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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