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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 43 (1994), S. 1052-1058 
    ISSN: 0006-3592
    Keywords: reversed micelle systems ; partition of proteins ; pH ; ionic strength ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Four proteins with different physicochemical properties have been partitioned in reversed micelle systems: thaumatin, ribonuclease A, soybean trypsin inhibitor, and α-lactalbumin. The organic phase was formed by sodium salt (AOT) in isooctane, and the aqueous phase contained KCl, KBr, MgCl2, or NaCl. Aqueous phase pH was varied between 2 and 13 and ionic strength from 0.1 to 1.0 M. Small changes in pH [around the isoelecric point (pl)] were found to influence the solubilization of ribonuclease A and trypsin inhibitor, but for thaumatin the pH change necessary to affect partition was much greater as a consequence of the difference in net charge (titration curves) of these protein molecules as pH changes. The type of ions present in the system was also a determining factor for partition; the larger ions (K+) produced more electrostatic screening and hence less protein solubilization than the smaller ions (Na+). With changes in ionic strength surface hydrophobicity was a dominant factor affecting solubilization of thaumatin in NaCl-containing systems at high pH. Charge distribution and hydrophobicity are thought to be important parameters when partitioning the protein α-lactalbumin. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 46 (1995), S. 69-79 
    ISSN: 0006-3592
    Keywords: esterification ; lauric acid ; geraniol ; Lipozyme ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The esterification of lauric acid with geraniol catalyzed by the commercially immobilized lipase preparation from Mucor miehei, Lipozyme®, was studied in well-stirred flasks. The enzyme support was characterized in terms of its internal and external surface area, protein location, and protein content. It was found that the enzyme was mainly located on the external surface of the support, therefore, internal diffusional limitations were not important. It was also shown that the protein content of the support depends on the size of the particle, with smaller particles containing higher amounts of protein per unit weight. Under the conditions studied, the reaction was not under external mass transfer limitations, and the initial reaction rate depended on the size of the support particles. This was mainly due to the different protein contents on the support as a function of particle size and not to internal or external mass transfer limitations. Also, it was found that the inhibition exerted by water was predominantly a physical effect due to its accumulation around the enzyme. It was also found that the reaction was substrate inhibited by lauric acid, but not by geraniol. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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