Immobilization of Paenibacillus macerans NRRL B-3186 cyclodextrin glucosyltransferase and properties of the immobilized enzyme

Cyclodextrin glucosyltransferase from Paenibacillus macerans NRRL B-3186 wa s immobilized on aminated polyvinylchloride (PVC) by covalent binding with a bifunctional agent (glutaraldehyde). The immobilized activity was affecte d by the length of the hydrocarbon chain attached to the PVC matrix, the am ount of the protein loaded on the PVC carrier, and glutaraldehyde concentra tion. The activity of the immobilized enzyme was 121 units/gram carrier, th e specific activity calculated on bound protein basis was 48% of the solubl e enzyme. Compared to the free enzyme, the immobilized form exhibited: a hi gher optimal reaction temperature and energy of activation, a higher K-m (M ichaelis constant) and lower V-max (maximal reaction rate), improved therma l stability and resistance to chemical denaturation. The operational stabil ity was evaluated in repeated batch process and the immobilized enzyme reta ined about 85% of the initial catalytic activity after being used for 14 cy cles. (C) 1999 Elsevier Science Ltd. All rights reserved.