Preparation and General Properties of Glucoamylase Bound to Halogenacetyl Cellulose

Abstract

The coupling reaction of glucoamylase and halogenacetyl cellulose (HAC) without pretreating with organic solvent led to form large particles of immobilized glucoamylase and the activity and the specific activity of the preparation were very low. However, the coupling reaction with HAC pretreated with organic solvents allowed to form very fine particles and the activity was increased by five times. The latter contained 3~6% of enzyme protein and the specific activity to maltose reached to 80~90% of native glucoamylase. Since the specific activity of the preparation was presumed to be much influenced by the particle size, the specific activity and general properties of different particle sizes were compared with those of native enzyme. The specific activities of particles of 0~15μ, 15~55μ, 70~190μ and 130~270μ showed 82%, 33%, 27% and only 7% of native enzyme, respectively. Km values of native form, 0~15μ, 15~55μ and 70~190μ particles were 0.90×10−3m, 1.35×10−3m, 1.60×10−3m and 2.1×10−3m in the case of maltose as substrate, respectively. The other properties of particles of 0~15μ were almost identical to those of native enzyme except for the effect of temperature on the reaction rate. However, pH activity, pH stability and urea stability of particles of 70~190μ were much inferior to those of native enzyme and particles of 0~15μ.