【摘要】 固定化酶是酵母表面展示技术的1个重要应用方向。本文应用食品级酵母展示表达系统进行表达,成功获得具有生物活性且固定在酿酒酵母细胞表面的β-1,3-1,4-葡聚糖酶,并测定其酶学性质。结果表明,与分泌表达的自由酶相比,展示表达的β-1,3-1,4-葡聚糖酶的酶学性质发生了改变。其最适温度为60℃,热稳定性增强。50℃保温3 h,对酶活几乎没有影响。60℃保温1 h后的酶活为初始酶活的129.2%。随着该温度下保温时间的延长,酶活迅速下降,保温3h后的酶活为初始酶活的64.6%。70℃保温1 h,酶活增加到初始酶活的109.2%;1 h后酶活开始下降;70℃保温3 h后残留酶活仅为初始酶活的35.8%。展示表达的β-1,3-1,4-葡聚糖酶最适pH为6.0,在pH 4~7范围内酶的稳定性较好。更多还原

【Abstract】 The Saccharomyces cerevisiae cell-surface display expression system is one kind of eukaryotic display system which expresses heterogeneous protein on the cell surface by immobilization. In this paper, the properties of displayed β-1,3-1,4-glucanase were studied. The results showed that the optimal temperature and pH of displayed enzyme was 60 ℃ and 6.0. The thermal stability of β-1, 3-1, 4-glucanase displayed in the recombinant yeast cells was enhanced compared to the free enzyme. The residual activity of β-1,3-1,4-glucanase in yeast cells increased with incubation time and reached 129.2% at 60 ℃ and 109.2% at 70 ℃ at 1 h, and then gradually decreased. After incubation for 3 h at 60 ℃ and 70 ℃, the enzyme activity still remained at 64.6% and 35.8%, respectively, which indicated an improved thermostability.更多还原