Bioaffinity immobilization of tannase from Aspergillus niger on concanavalin A-Sepharose CL-4B

Tannase from Aspergillus niger van Teighem was immobilized on concanavalin A-Sepharose via bioaffinity interaction. The immobilized enzyme showed a pH optimum similar to that of the free enzyme. Km values for free and immobilized enzyme were 0.3 and 0.6 mM respectively. Vmax changed from 0.013 to 0.02 (mu)mol·min^-1 upon immobilization. The immobilized preparation was quite stable to reuse, there was no loss of enzyme activity after three cycles and it retained 81% activity even after the sixth cycle. Ester hydrolysis using the immobilized enzyme led to a 40% conversion into gallic acid as compared with 30% obtained with the free enzyme.