食品科学 ›› 2013, Vol. 34 ›› Issue (9): 127-134.doi: 10.7506/spkx1002-6630-201309027

• 生物工程 • 上一篇    下一篇

肝素黄杆菌硫酸软骨素酶AC的高效重组表达体系构建及其酶学性质研究

吴敬君1,李 晔1,2,张 翀1,李 梅1,邢新会1,*   

  1. 1.清华大学化学工程系 工业生物催化教育部重点实验室,生物化工研究所,北京 100084;
    2.北京电子科技职业学院生物技术系,北京 100029
  • 收稿日期:2013-04-03 修回日期:2013-04-22 出版日期:2013-05-15 发布日期:2013-05-07
  • 通讯作者: 邢新会 E-mail:xhxing@tsinghua.edu.cn
  • 基金资助:

    国家“863”计划项目(2012AA022201);北京市属高等学校人才强教计划项目(PHR201107151);
    北京电子科技职业学院院内重点课题(YZKB2011003);北京市属高等学校人才强教深化计划资助项目

Gene Cloning and Recombinant Expression of Chondroitinase AC from Pedobacter heparinus and Characterization of Recombinant Fusion Enzyme

WU Jing-jun1,LI Ye1,2,ZHANG Chong1,LI Mei1, XING Xin-hui1,*   

  1. 1. Key Laboratory for Industrial Biocatalysis, Ministry of Education, Institute of Biochemical Engineering, Department of Chemical
    Engineering, Tsinghua University, Beijing 100084, China;2. Department of Biotechnology, Beijing Electronic Science and
    Technology Vocational College, Beijing 100029, China
  • Received:2013-04-03 Revised:2013-04-22 Online:2013-05-15 Published:2013-05-07
  • Contact: XING Xin-hui E-mail:xhxing@tsinghua.edu.cn

摘要:

为实现硫酸软骨素酶AC(chondroitinase AC,ChonAC)在大肠杆菌中高效表达,通过PCR方法从肝素黄杆菌(Pedobacter heparinus)中扩增得到ChonAC基因cslA,采用融合蛋白技术构建麦芽糖结合蛋白(maltose-bindingprotein,MBP)与ChonAC的融合表达载体(MBP-ChonAC),并在低温(15℃)条件下实现MBP-ChonAC的可溶活性表达,通过MBPTrap HP可实现一步纯化,使纯度可达95%以上,酶比活力可达94.1IU/mg融合蛋白(即相当于143.8IU/mgChonAC蛋白当量)。对MBP-ChonAC的酶学研究发现,其最佳催化pH值为7.5~8.0,最佳Ca2+浓度为20mmol/L,最适NaCl浓度为50mmol/L,最佳作用温度为20~35℃。MBP-ChonAC具有较好的热稳定性,在30℃时其半衰期可达8.3h。同时对其以硫酸软骨素A为底物的动力学常数测定发现,MBP-ChonAC相比ChonAC其Km稍有增大而催化常数kcat稍有降低,但是差别不大,表明MBP的融合没有对ChonAC的催化能力造成影响。通过宿主优化、诱导浓度优化及培养基优化进一步提高了MBP-ChonAC的表达量,其摇瓶培养酶活力就可达10800.5IU/L。

关键词: 亲和纯化, 硫酸软骨素酶AC, 酶学性质, 表达量优化, 麦芽糖结合蛋白, 重组表达

Abstract:

Chondroitinase AC (ChonAC) is an important enzyme to reveal the biological function, structure and mechanism
of chondroitin sulfate, and it is important for low molecular weight chondroitin sulfate preparation and diseases treatment.
To achieve the efficient expression of ChonAC with high activity in recombinant Escherichia coli (E. coli), the ChonAC
gene (cslA) from Pedobacter heparinus was amplified by polymerase chain reaction (PCR), and the fusion expression vector
for expressing maltose-binding protein (MBP) fused ChonAC (MBP-ChonAC) was constructed. The results showed that the
fusion strategy using MBP was effective to enhance the solubility of the MBP-ChonAC when induced at low temperature of
15 ℃, the purity and the specific activity of MBP-ChonAC could reach 95% and 94.1 IU/mg-fusion protein (equivalent to
143.8 IU/mg ChonAC) by one-step MBPTrap HP purification, respectively. The enzyme characteristic study showed that the
optimum pH value, Ca2+concentration, NaCl concentration, and reaction temperature was 7.5—8.0 , 20 mmol/L, 50 mmol/L,
and 20—35 ℃, respectively. The half-life of MBP-ChonAC could reach 8.3 h at 30 ℃. The kinetic characterization showed
that the Km was higher while the kcat was a little bit lower than the reported native ChonAC for chondroitin sulfate A, while
the biocatalysis experiment for MBP-ChonAC indicated that the fusion of ChonAC with MBP did not affect the enzyme
function. Furthermore, the total activity of MBP-ChonAC by shake flask cultivation could reach 10800.5 IU/L, the highest
value reported so far, through the optimizations of host cells, IPTG induction concentration, and M9-based culture medium.

Key words: affinity purification, chondroitinase AC (ChonAC), enzymatic characteristics, expression level optimization, maltose-binding protein (MBP), recombinant expression

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