嗜热真菌 Thermomyces lanuginosus热稳定a—淀粉酶的纯化及特性  

PURIFICATION AND PROPERTIES OF A THERMOSTABLE α-AMYLASE FROM THE THERMOPHILIC FUNGUS THERMOMYCES LANUGINOSUS

作　　者：李多川[1] 杨依军[1] 彭友良[1] 沈崇尧 周培瑾[2] 黄亦存[2] 

机构地区：[1]中国农业大学植病系,北京100094 [2]中国科学院微生物研究所,北京100080

出　　处：《微生物学报》1997年第2期107-114,共8页Acta Microbiologica Sinica

基　　金：国家教育委员会高等学校博士点基金资助。

摘　　要：嗜热真菌Thermomyces lanuginosus在液体培养基中于50℃静止培养14d,培养液经硫酸铵分级沉淀、DEAE-Toyopearl离子交换层析、Butyl-Toyopearl疏水层析、SephacrylS-300分子筛层析和FPLC MonoQ离子交换层析,得到了凝胶电泳均一的淀粉酶。纯酶与淀粉反应不同时间后,用碘色反应法和DNS法测定淀粉和还原糖量,结果显示淀粉量在开始时迅速下降,但还原糖的量却增加很慢;产物经TLC层析分析为麦芽糖和少量葡萄糖。由此说明它为α-淀粉酶。用SDS-PAGE和Sephacryl S-300分子筛层析测定分子量为56000,不具亚基。酶反应最适温度和pH分别为65℃和4.5～5.0。在pH4.6条件下,酶在50℃是稳定的;60℃保温1h,仍保留94％的原酶活性;酶在70℃的半衰期为10min。钙离子对酶有激活作用。酶对糖原和糊精有一定的水解能力。A thermostable α-amylase from the culture supernatant from 14-day-old static cultures grown on soluble starch of the thermophilic fungus Thermomyces lanuginosus was purified to SDS-PAGE homogenous by ammonium sulfate fraction, DEAE-Toyopearl chromatography, Butyl-Toyopearl chromatography, Sephacryl S-300 chromatography and FPLC MonoQ chromatography. The hydrolysis of soluble starch by the purified a-amylase resulted in maltose and glucose as the end production. The molecular weight of the enzyme estimated with SDS-PAGE and Sephacryl S-300 was 56000. The optimum condition for activity were pH4.5-5.0, temperature 65℃. The α-amylase was thermostable at 50 ℃. The enzyme retained 94% activity after 1 h at 60 ℃. The half life time of the enzyme was 10 min at 70 ℃. The addition of Ca2+ had a stabilizing effect on the enzyme. Soluble starch was completely degraded by the α-amylase, whereas glycogen and dextran were hydrolysed to a lesser extent.

关 键 词：嗜热真菌 THERMOMYCES LANUGINOSUS Α淀粉酶 

分 类 号：Q939.503[生物学—微生物学]