黑曲霉突变菌株产糖化酶的酶学特性表征

Enzymatic Characterization of Glucoamylase from Aspergillus niger Mutant

以电子束诱变黑曲霉突变菌株为对象,通过最适pH试验、最适作用温度试验、热稳定性试验、酸碱稳定性试验和金属离子对糖化酶活力影响的试验,探明黑曲霉电子束突变菌株产糖化酶的酶学特性。结果表明:突变菌株产糖化酶酶最适作用温度为63℃,且最高酶活较原始菌株提高26%,在80℃原始菌株所产糖化酶失活时,仍有8.4 kU/mL酶活剩余,突变菌株所产的糖化酶的热稳定性明显提高。突变菌株所产糖化酶最适pH为4.6,且最高酶活较原始菌株提高24%,在原始菌株所产糖化酶失活时仍有6.9 kU/mL酶活剩余,突变菌株糖化酶的pH稳定性有着明显提高。K^+、Mg^(2+)、Ca^(2+)可在一定程度上增强其活力;Ag^+、Fe^(2+)、Cu^(2+)则在不同程度上抑制糖化酶活力;Zn^(2+)、EDTA对其酶活力影响较小或无明显现象。

Mutant strain of Aspergillus niger by electron beam was selected to be the object. To explore the enzymatic characteristics of glucoamylase produced by mutant strain of Aspergillus niger by the optimum pH test, the optimum temperature test, thermal stability test, acid-base stability test and the expetiment on the offect of metal ions on the activity of glucoamyase. The results showed that glucoamylase was produce at 63 ℃ and the highest enzyme activity was 26% higher than the original strain.8.4 kU/mL enzyme activity was remained when the glucoamylase produced by the mutant strain was inactivated at 80 ℃, the themal stability of the glucoamylase produced by the mutant strain is obviously improved.The optimum pH of glucoamylase from Aspergillus niger Mutant was 4.6, and the highest enzyme activity was 24%, which higher than that of the glucoamylase from original strain.When the glucoamylase produced by the original strain was inactivated ,there were still 6.9 kU/mL enzyme activity remained, the pH stability of the glucoamylast was produced by the mutant strain was obviously improved.Its activity was increased by K＋ ,Mg2＋ ,Ca2＋ to a certain extent,and inhibited by Ag＋ ,Fe2＋ ,Cu2＋ to varying degrees,had little and or no significant effect by Zn2＋ , EDTA.