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  • Biochemistry and Biotechnology  (2)
  • extraction of intracellular enzymes  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Studies on the isolation of penicillin acylase from Escherichia coli by aqueous two-phase partitioning (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 40 (1992), S. 517-524 
    Details
    ISSN: 0006-3592
    Keywords: aqueous two-phase ; penicillin acylase ; polyethylene glycol ; polyethylene glycol derivatives ; affinity partitioning ; enzyme release ; extraction of intracellular enzymes ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A method of enzyme release and aqueous two-phase extraction is described for the separation of penicillin acylase from Escherichia coli cells. Butyl acetate, 12% (v/v), treatment combined with freeze-thawing gives up to 70% enzyme release. For polyethylene glycol (PEG) + phosphate two-phase extraction systems the enzyme purity and yield were rather low. Modified PEG, including PEG-ampicillin, PEG-aniline, PEG-phosphate, and PEG-trimethylamine, were synthesized and used in aqueous two-phase systems; PEG-trimethylamine is the most satisfactory. A system containing 12% (w/w) PEG4000, 8% (w/w) of which is PEG-trimethylamine, with 0.7M potasium phosphate at pH 7.2, resulted in the enzyme selective partition being greatly enhanced by charge directed effects. Possible mechanisms for the separation process are discussed. © 1992 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260400410
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  • 2
    Electronic Resource
    Electronic Resource
    Fluorescence imaging detection for capillary isoelectric focusing (1995)
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 1474-1478 
    Details
    ISSN: 0173-0835
    Keywords: Capillary isoelectric focusing ; Imaging detection ; Laser induced fluorescence ; Proteins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A simple laser-induced fluorescence (LIF) imaging detector and an ultrasensitive LIF imaging detector are described for capillary isoelectric focusing (CIEF). An argon ion laser beam of 496.5 nm is used as excitation source. In the simple LIF imaging detector, the excitation beam is directed into a capillary column by an optic fiber array. In the ultrasensitive LIF imaging detector, the laser beam is first expanded, then is focused into the 4.5 cm long capillary column by a cylindrical lens. Fluorescence emission is detected by a charge-coupled device (CCD) camera. The feasibility and performance of the LIF imaging detector system for CIEF are first verified with a naturally fluorescent protein, b-phycoerythrin. Then, the ultrasensitive LIF imaging system is used as a detector for CIEF of proteins labeled with fluorescein isothiocyanate (FITC). Three FITC-labeled proteins (i) α-D-galatosylated FITC-albumin, (ii) insulin-FITC, and (iii) casein-FITC, are used as model samples. Fluorescence images of the model samples are measured during the CIEF process. The focusing of the protein samples is complete in about 1.5 min. The ultrasensitive detector's detection limits for the FITC-labeled proteins are at the level of 10-10 M, and the mass detection limits are about 4.5 × 10-17 mole, even though only 10% of the fluorescence emission is collected. Therefore, the method is capable of separating and detecting 10-11 M or amole (10-18 mole) level protein samples with a band-pass filter more specific to the fluorescence light. Potential applications of the LIF imaging system in addition to quantitation of separated fluorescent species in various capillary electrophoresis methods can also include investigation of interaction between analytes focused in a capillary column.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.11501601244
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