Preparation and Enzymatic Properties of Aspergillus niger Endoinulinase Immobilized onto Various Polysaccharide Supports

Abstract

An extracellular endoinulinase P-III from Aspergillus niger 12 has been immobilized covalently onto bromoacetyl-cellulose (BAC), cellulose-carbonate (CC) and CNBr-activated Sepharose 4B (CAS) with the activity yields of 11.9, 24.1 and 19.3%, respectively, under optimal reaction conditions for the immobilization. All three immobilized enzymes increased the resistance to inactivation by p-chloromercuribenzoate or Fe³⁺. Mn²⁺ stimulated the activities of the immobilized endoinulinases onto CC (160%) and CAS (168%) more remarkably than those of free and BAC-immobilized enzymes (124%). The marked rise from 45 to 60°C in the optimal temperature for inulin hydrolysis was observed in the CAS-immobilized enzyme. The pH stability decreased on the acidic side and increased slightly on the alkaline side in the BAC-immobilized enzyme, and shifted to the acidic side in the CC-immobilized enzyme. The K_m value decreased in the BAC-immobilized enzyme and increased in the CAS-immobilized enzyme.