大肠杆菌碱性磷酸酶的体外定向进化研究  

The In vitro Directed Evolution of E.coli Alkaline Phosphatase

作　　者：徐卉芳[1] 张先恩[2] 张治平[2] 张用梅[2] A.E.G.CASS 

机构地区：[1]中国科学院微生物研究所,北京100080 [2]中国科学院武汉病毒研究所,武汉430071 [3]Biochemistry Department

出　　处：《生物化学与生物物理进展》2003年第1期89-94,共6页Progress In Biochemistry and Biophysics

摘　　要：大肠杆菌碱性磷酸酶 (E .colialkalinephosphatase,EAP ,EC 3 1 3 1)是一个非特异性二聚体磷酸单酯酶 .采用易错聚合酶链反应 (errorpronePCR)的方法 ,在原有高活力突变株的基础上 ,对EAP远离活性中心催化三联体的区域进行定向进化 ,经两轮errorpronePCR ,获得催化活力较亲本D10 1S突变株提高 3倍、较野生型酶提高 35倍的进化酶 4 186 ,并对该酶的催化动力学特征进行了分析 .进化酶基因的DNA测序表明 4 186含两个有义氨基酸置换 :K16 7R和S374C ,二者既不位于底物结合位点 ,也不位于酶的金属离子结合位点 .The evolution of phoA gene fragment distant from the Asp101-Ser102-Ala103 encoding region to increase the catalytic activity of EAP with a single mutant D101S as parent was directed. Through two cycles of error prone PCR, coupled with a sensitive screening method, an evolved variant 4-186 was obtained. Its catalytic activity was 3-fold higher than that of D101S parent and 35-fold more active than wild-type EAR The kinetic analysis indicated that the evolved enzyme exhibits a higher substrate binding ability and a higher catalytic efficiency than the D101S parent enzyme. DNA sequence revealed that 4-186 contains two amino acid substitutions, K167R and S374C, both of which locate neither the substrate-binding sites nor the metal-binding sites of EAP.

关 键 词：大肠杆菌 碱性磷酸酶 体外定向进化 催化活力 

分 类 号：Q814[生物学—生物工程] Q936