高温放线菌莱斯氏属RHA1菌株产低分子量α-淀粉酶的初步研究  

Purification and Characterization of a Novel Low Molecular Weight α-amylase from Thermophilic actinomycete Strain Laceyella sp.RHA1

作　　者：朱国东[1] 陈波[1] 张兰兰[1] 季秀玲[1] 魏云林[1] 林连兵[1] 

机构地区：[1]昆明理工大学生物工程技术研究中心,昆明650224

出　　处：《生物技术通报》2011年第10期199-205,共7页Biotechnology Bulletin

基　　金：国家自然科学基金资助项目(30660009;30960022)

摘　　要：嗜热放线菌莱斯氏属RHA1菌株发酵液经过(NH4)2SO4(饱和度为60%)沉淀后,经过分子筛层析纯化获得一种低分子量α-淀粉酶,分子量为11.2 kD。对此酶研究表明,其pH值范围为4.5-11.5,在pH值为5.5-6.5之间酶活性较高,最大酶活性的pH值为6.0;此酶在缺乏Ca2+时,最适温度为55-60℃,当加入Ca2+后,相对最适温度上升至65℃;然而EDTA(10 mmol/L)可使此酶的酶活性降低98%,同样在Ni2+、Ag2+和Fe2+条件下酶活性也受到干扰;此α-淀粉酶具有淀粉内切酶活性,水解直链淀粉和支链淀粉的主要产物为小分子低聚糖(D2-D3)。An α-amylase with low molecular weight was purified from a thermophilic actinomycete strain Laceyella sp.RHA1.The α-amylase could be purified in one step using size-exclusion chromatography after concentrating of crude enzyme by salting out with（NH4）2SO4（60% saturation）.The purified alpha-amylase had a molecular weight of 11.2 kD,which is the lowest one among alpha-amylases.This enzyme had high activity in a pH range from 5.5 to 6.5,with optimum at 6.0.It was stable in a wide pH range between 4.5 and 11.5.The optimum temperature of enzyme activity was 55-60℃ in the absence of Ca2＋.In the presence of Ca2＋,the optimum temperature shifted to 65℃.Ca2＋ could enhance the activity and stability of the enzyme,however,98% of the activity lost in the presence of EDTA（10 mmol/L）.Ni2＋,Ag2＋ and Fe2＋ severely inhibited the enzymes activity indicating the role of sulfydryl group in catalysis.This alpha-amylase displayed an endolytic activity and small maltooligosaccharides（D2-D3）were formed predominantly when soluble starch and amylopectin were used as substrates.

关 键 词：嗜热放线菌 莱斯氏属 小分子量α-淀粉酶 酶学特征 

分 类 号：TQ925[轻工技术与工程—发酵工程]