Abstract

Baker yeast invertase, chemically modified with chitosan, was immobilized on hyaluronic-acid-coated chitin support via polyelectrolyte complex formation. The immobilized enzyme retained 80% of the initial invertase activity. The optimum temperature for sucrose hydrolysis was increased by 5C, and its thermostability was enhanced by about 10C after immobilization. The immobilized enzyme was stable against incubation in high-ionic-strength solutions, and was sixfold more resistant to thermal treatment at 65C than the native counterpart. The biocatalyst prepared retained 100% after 10 cycles of reuse as well as after 74 h of continuous sucrose hydrolysis in a packed bed reactor, respectively. The immobilized enzyme retained 69% of its activity after 50 days of storage at 37C. © 2008, Blackwell Publishing.