Studies On The Immobilization Of β-Galactosidase On Biomacromolecule Microspheres

Immobilization enzymes offer advantages over free enzymes in terms of choice of batch or continuous processes, rapid termination of reactions, controlled product formation, ease of enzyme removal from the reaction mixture and adaptability to various engineering designs. In this paper, the immobilization methods, properties and usage of immobilized enzyme were introduced. The methods can be divided into five basic groups:(1) covalent attachment to solid supports, (2) adsorption to solid supports, (3) entrapment within polymeric gels, (4) cross-linking to solid supports with biofunctional reagents, (5) encapsulation of enzymes within membranes permeable only to substrates and products. Studies on modified carrier--magnetic polymer microspheres were summarized. It is pointed out that the new type, high efficiency immobilized enzyme technology by modificating natural polymer support and combining with the present new technology will be the development of future research.Two kinds of microspheres, composite microspheres and composite magnetic microspheres, have been synthesized based on artemisia seed gum, chitosan and magnetic fluid using the suspension cross-linking technique. The properties of the microsperes, such as morphological, thermal stability, magnetic properties, swelling kinetics and pH responsive behaviors were characterized by different techniques.The Immobilization ofβ-galactosidase was cross-linked with glutaraldehyde on the microspheres described above. The research was conducted into pH and addition of enzyme amount on immobilization of enzyme, the optimal conditions in the experiment were gained; Besides, a study was conducted of nature of immobilized enzyme to find that the pH and temperature of the immobilized enzyme appears to be higher than those of free enzymes, which has better thermal stability and smaller Km than free enzyme.