Enzyme Immobilization on Carbon Felt
The concept of the membrane reactor has been increasingly researched in recent years because it has been postulated that the membrane core of a filtration membrane could itselfbe a reactive phase. Thus, the membrane would bring in addition the ability to chemically transform compounds that are solubilized in the permeate. This type of chemical transformation is very efficient because the process is a catalytic one.
We have already described the immobilization of biotinylated enzymes by a specific and irreversible biotin-avidin molecular recognition process. We generalized this process of enzyme immobilization to another enzyme
(i.e., catalase), which has been biotinylated prior to membrane immobilization because catalase is not a commercially available biotinylated enzyme. We have measured the kinetic parameters of the enzymatic reaction (hydrogen peroxide dismutation) in the membrane system. A comparison of the deduced rate parameters with those of the free respective enzymes reveals a slight decrease in the reactivity of the enzymes immobilized on the polypyrrole membrane compared to that of the free enzymes, but far from the loss of reactivity generally observed until now with enzymes immobilized by using more classical routes such as chemical bonding. Moreover, the long-term stability of the membrane in terms of reactivity also appeared to increase.
Electrochemical polymerization of the pyrrole-biotin monomers was carried out in a classical three-electrode cell, the same as those commonly used in cyclic voltammetry experiments. The working electrode was carbon felt (1.5 X 05 X 0.5 cm). Hydrogen peroxide dismutation was achieved with aflow of 30 cm3 hydrogen peroxide 10-2Msolutionacrossamembraneheld in a column, as shown in Fig. 24.
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