Covalent immobilization of a glucoamylase to bagasse dialdehyde cellulose

Cellulose fibres from bagasse were oxidized by sodium periodate in sulphuri c acid media at positions 2 and 3 of the anhydroglucose unit to produce dia ldehyde cellulose. The aldehyde groups of the dialdehyde cellulose were abl e to react with amino groups of a glucoamylase to form covalent bonds and r esult in a dialdehyde cellulose immobilized enzyme. The optimum pH of this immobilized enzyme and free enzyme were in the range of 3.0-5.0 and 3.5-5.0 , respectively. The optimum temperature for both the free and immobilized e nzymes was 60-65 degreesC. The relative remaining activity of the immobiliz ed enzyme was 36% and its stability was very good, since it could be reused for over 30 cycles. Its activity decreased from the first to the seventh r euse cycles, due to the slow detachment of non-covalently bound enzyme. How ever, activity tended to stabilize after the seventh cycle of reuse, indica ting very stable covalent binding between the enzyme and dialdehyde cellulo se.