Immobilization of trypsin on sand: Mode of binding

Acid-washed and heat-treated river sand was separated into different fractions by geochemical methods and immobilization of trypsin was carried out on the separated fractions using 3-aminopropyltriethoxysilane and glutaraldehyde. Scanning Electron Micrographs of the purified fraction (Sp. gr >2.5 and <2.8) of magnetically non-susceptible sand and quartz showed that the enzyme could be fixed on the supports. Malonic acid (16.3 nmol and 16.7nmol per g) appeared to be bound to alkylamine purified fraction of magnetically non-susceptible sand and alkylamine quartz, respectively. Studies on the effect of 6 M guanidine.HCl on immobilized trypsin demonstrated that immobilized trypsin had considerable stability against denaturation. The results obtained indicated that magnetically non-susceptible sand was found to be nearly as good as quartz for trypsin immobilization and that trypsin was covalently coupled to sand via 3-aminopropyltriethoxysilane and glutaraldehyde.