Sum m aryFour silica supports differing in pore dimensions were activated by treatment with SiCI, and then with ethylenediamine to obtain alkylamine groups on the silica surface. Three enzymes, peroxidase from cabbage, glucoamylase from Aspergillus niqw C and urease from sQybean were immobilized on these supports using glutaraldehyde as coupling agent. It was found that the protein content, the retained enzymatic activity and the storage stability of the silica supported enzymes were considerably affected by support pore size and enzyme molecular weight, the factors which are supposed to alter protein distribution inside the support pores. The highest activity was found for peroxidase and glucoamylase attached to the silica with the widest pores, but their loss in activity during storage was considerable. The urease retained less activity after immobilization, but its storage stability was excellent.
Three types of organic polymers and bead‐shape silica gels were activated by graft polymerization of 2,3‐epoxypropyl methacrylate; in some cases, epoxide groups on the support surface were modified to NH2 groups. Eight active matrices so obtained were assessed as supports for immobilized enzymes using peroxidase, glucoamylase and urease. The immobilization yield of protein and specific activities of enzymes were better with supports containing NH2 groups than with those containing epoxide spacer arms. Maximum enzyme immobilization and storage stabilities were obtained with silica‐gel beads activated by graft polymerization of 2,3‐epoxypropyl methacrylate. With all eight matrices tested, the immobilized enzymes showed good stability with not less than 82% of the original activity persisting after 28 days. The developed matrices have potential for use in process‐scale biotechnological operations.
Several alkylaminated porous silica gels and acrylic type porous polymers have been used for covalent binding of fungal peroxidase from Trumetes versicolor. The immobilization efficiency expressed in terms of the bound protein content, specific enzyme activity, and enzyme storage stability have been determined for both types of supports used. The results indicate a better immobilization ability of organic polymers in comparison with silica gels.
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