A Comparative Study of the Structural and Kinetic Properties of Papain Immobilized on Modified Polysulfone and Modified Cellulose Acetate Membranes
In order to determine if the chemical nature of the polymeric membrane were a factor in the conformation of bound enzymes, electron paramagnetic resonance (EPR) spin labeling techniques using a short, active-site specific spin label have been employed to study the properties of a model enzyme, papain, immobilized on fully-hydrated modifiied polysulfone membranes, hydrophobic, or modified cellulose acetate membranes, hydrophilic. The properties of the immobilized enzymes are compared with that of the free enzyme in solution. Both polysulfone and cellulose acetate membranes provide some stability for papain, but in general hydrophoilic cellulose acetate membranes give papain properties more similar to those of papain in aqueous solution.
This study reports the development of an effective method to acquire EPR spectra of fullyhydrated, spin labeled enzymes immobilized on polymeric membranes. All these findings indicate that the EPR spin labeling technique provides a powerful method for studying immobilized enzyme systems. Furthermore, understanding the dependence of the properties of the immobilized enzyme on the characteristics of the polymeric membrane may be helpful in the selection of support matrices for particular applications of mnembrane-based enzyme bioreactors, affnity membranes, and biosensors.
KeywordsElection Paramogmeter Resonance Election Paramogmeter Resonance Spectrum Election Paramogmeter Resonance Signal Spin Label Guanidine Hydrochloride
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