α-葡聚糖酶的酶学性质初步研究

α-葡聚糖酶能够很好地解决制糖工业中的葡聚糖问题，在制糖工艺过程通过添加α-葡聚糖酶去除α-葡聚糖是目前最佳选择。本文初步研究了基因工程菌株GSll5-dex生产的。α-葡聚糖酶的酶学性质。结果显示：该酶的最适反应温度为50℃；最适反应pH为5．0；FeH、Mg2＋和Co2＋对酶有激活作用，Ca2＋、Kr＋、Zn2＋、Na＋、Al3＋的作用不明显，而Cu2＋、Ba2＋、Fe2＋、Sn2＋、Ag＋对酶有抑制作用；30℃以下保存28h酶活损失很小，而40℃保存16h，就已损失60％，在45℃保存30min，就已损失56％，保存温度越高，酶活损失越快；该酶在pH为4～6的范围内较稳定，高浓度蔗糖对该酶起到很好的保护作用，甘油次之，氯化钠基本没有保护作用。

Study on the Enzymatic Properties of Dextranase

Dextran not only causes severe economic losses due to sugar loss,but also causes processing problems.The only method applicable today in the sugar industry is the enzymatic hydrolysis of dextrans.This paper studied on the enzymatic properties of dextranase produced by recombinant Pichia pastoris GS115-dex.The results showed that,the optimum temperature of dextranase was 50℃ and the optimum pH is 5.0.Fe3+,Mg2+and Co2+ activated the enzyme;Ca2+,K+,Zn2+,Na+ and Al3+can’t work effectively;Cu2+,Ba2+,Fe2+,Sn2+ and Ag+ inhibited the enzyme.Under 30℃ for a long time,the enzyme can still maintain its activity,placed on 40 ℃ for16 h the enzyme had lost 60% and placed on 45℃ for30 min the enzyme had lost 56%,the higher the temperature,the faster the activity loss.This enzyme is more stable in the range of pH 4～6,the high concentration of sucrose in the enzyme plays a very good protective effect,followed by glycerol,and sodium chloride have no protective effect.