New and strong ionic exchange resins have been prepared by the simple and rapidionic adsorption of anionic polymers (sulfate-dextran) on porous supports activatedwith the opposite ionic group (DEAE/MANAE). Ionic exchange properties of suchcomposites were strongly dependent on the size of the ionic polymers as well as onthe conditions of the ionic coating of the solids with the ionic polymers (optimalconditions were 400 mg of sulfate-dextran 5000 kDa per gram of support). Around80% of the proteins contained in crude extracts from
Escherichia coli and
Acetobacterturbidans could be adsorbed on these porous composites even at pH 7. This interactionwas stronger than that using conventional carboxymethyl cellulose (CMC) and evenothers such as supports coated with aspartic-dextran polymer. By means of thesequential use of the new supports and supports coated with polyethyleneimine (PEI),all proteins from crude extracts could be immobilized. In fact, a large percentage (over50%) could be immobilized on both supports. Finally, some industrially relevantenzymes (
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-galactosidases from
Aspergillus oryzae,
Kluyveromyces lactis, and
Thermussp. strain T2, lipases from
Candida antarctica A and
B, Candida rugosa,
Rhizomucormiehei, and
Rhyzopus oryzae and bovine pancreas trypsin and chymotrypsin) havebeen immobilized on these supports with very high activity recoveries and immobilization rates. After enzyme inactivation, the protein could be fully desorbed from thesupport, and then the support could be reused for several cycles. Moreover, in someinstances the enzyme stability was significantly improved, mainly in the presence oforganic solvents, perhaps as a consequence of the highly hydrophilic microenvironmentof the support.