食品科学 ›› 2012, Vol. 33 ›› Issue (11): 200-204.doi: 10.7506/spkx1002-6630-201211043

• 生物工程 • 上一篇    下一篇

Thermococcus siculi HJ21 α - 淀粉酶Asp186定点突变对酶活性的影响

吕明生1,杨 帆1,2,胡建恩2,房耀维1,焦豫良1,王淑军1,*,刘 姝1   

  1. 1.淮海工学院海洋学院 2.大连海洋大学食品工程学院
  • 出版日期:2012-06-15 发布日期:2012-07-27
  • 基金资助:
    江苏省高校自然科学研究重大项目(09KJA170001);江苏省科技支撑计划项目(BE2008340); 江苏省高校自然科学基础研究项目(08KJB550001)

Effect of Site-Directed Mutagenesis of Asp186 on Activity of Thermococcus siculi HJ21 α-Amylase

LU Ming-sheng1,YANG Fan1,2,HU Jian-en2,FANG Yao-wei1,JIAO Yu-liang1,WANG Shu-jun1,*,LIU Shu1   

  1. (1. College of Marine Science, Huaihai Institute of Technology, Lianyungang 222005, China ; 2. College of Food Engineering, Dalian Ocean University, Dalian 116023, China)
  • Online:2012-06-15 Published:2012-07-27

摘要: 为确定超嗜热古菌Thermococcus siculi HJ21α-淀粉酶(TSA)中特定氨基酸及所在位点与酶活性间的关系,以含TSA基因的pEt-28a-His6质粒为模板,利用定点突变技术,将第186位点的天冬氨酸(Asp)突变为天冬酰胺(Asn),突变子转化至E. coli BL21(DE3)并经IPTG诱导表达,测定突变前后的酶活性,定点突变后的TSA无酶活性;采用DNAStar和Deepview蛋白分析软件,预测突变前后TSA蛋白的二级结构和三级结构,结果表明Thermococcus siculi HJ21α-淀粉酶的186位点对维持TSA的酶活性具有重要意义,它的突变导致酶蛋白二级结构组件及氢键网络的改变。

关键词: α-淀粉酶, 定点突变, TSA基因, 186位点, 酶活性

Abstract: In order to determine the relationship between amino acid residue at the special site and the activity of Thermococcus. siculi HJ21 α-amylase, pEt-28a-His6 plasmid with TSA gene was used as a template for the site mutagenesis from Asp186 to Asn186. The activity of α-amylase with and without mutation was measured. According to the difference between per-mutant and mutant cDNA sequences, the secondary structure and three-dimensional structure of TSA protein were also predicted using DNAStar and Deepview protein analysis software. The results showed that Asp186 was of critical significance for maintaining the activity of T. siculi HJ21 α-amylase. The site-directed mutagenesis of T. siculi HJ21 α-amylase at position 186 changed the properties of secondary structure as well as hydrogen-bonding networks, thus resulting in the loss of its activity.

Key words: α-amylase, site-directed mutagenesis, TSA gene, position 186, enzymatic activity

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