Applications of magnetoproteoliposomes in bioreactors operating in high-gradient magnetic fields

© 1996 by CRC Press, Inc. A computer search! of the literature from 1967 to 1976 using the keywords “enzyme(s)” and “immobilization” recorded 658 hits, whereas the same search just 10 years later (1977 to 1986) scored 2538 hits. This publication bonanza has ofcourse inspired many review article and handbook writers. Concomittantly, the unique catalytic properties exhibited by enzymes have been harnessed in many industrial applications, particularly in the design of enzyme bioreactors.2 A close look at the type of enzyme used, however, reveals that most applications deal with so-called water-soluble enzymes, although numerous membraneassociated enzymes can also be very useful in many biotechnological processes.3-9 Most purification and immobilization protocols used for water-soluble biocatalysts, however, are, in general, not applicable to enzymes which in vivo are intimately associated with membranes. Membranebound enzymes indeed expose highly hydrophobic regions on their surface so that they tend to aggregate continuously during the consecutive purification and immobilization steps, often resulting in irreversible loss of enzyme activity. In addition, for an acceptable degree of activity, membrane-bound enzymes must be surrounded by a lipidic environment.10-12 Until now, industrial processes aimed at exploiting the catalytic potential of intrinsic membrane enzymes could only circumvent these problems by using whole cells or cell fragments. A main drawback, often encountered in using whole cells, is product contamination caused by unwanted side-reactions (e.g., by further metabolism ofthe desired product), due to the presence of cell fragments, or of nutrients, required to sustain the viability of the cells. In addition, the performance of immobilized cell preparations may be adversely affected by the action of intracellular proteases, by diffusional limitations, etc.

ISBN:0849340128

Jaar van publicatie:2018