以包涵体形式表达的6B11卵巢癌抗独特型单链抗体的复性、纯化和活性研究

RENATURATION, PURIFICATION AND ACTIVITY OF 6B11 OVARIAN CARCINOMA ANTI IDIOTYPIC ANTIBODY scFv EXPRESSED AS INCLUSION BODIES IN E.coli

目的：探讨以细菌胞浆内包涵体形式表达的６Ｂ１１卵巢癌抗独特型单链抗体（６Ｂ１１ｓｃＦｖ）的复性、纯化及其活性。方法：重组质粒ｐＬ６Ｂ１１ｓｃＦｖ转化大肠杆菌ｐｏｐ２１３６，温度诱导，以包涵体形式获高效表达。超声破碎细菌细胞得包涵体，用８ｍｏｌ·Ｌ－１尿素溶解包涵体后直接稀释复性，探讨复性条件并采用ＤＥＡＥＳｅｐｈａｒｏｓｅＦａｓｔＦｌｏｗ离子交换层析纯化复性蛋白，ＳＤＳＰＡＧＥ分析蛋白纯度，Ｗｅｓｔｅｒｎｂｌｏｔ、ＥＬＩＳＡ及竞争抑制ＥＬＩＳＡ测活性。结果：复性蛋白质经纯化，纯度达９５％以上。当氧化型谷胱甘肽（ＧＳＳＧ）浓度为５ｍｍｏｌ·Ｌ－１，还原型谷胱甘肽（ＧＳＨ）浓度为０．５ｍｍｏｌ·Ｌ－１，１０℃复性４８ｈ以上时，复性率较高。纯化后的表达蛋白６Ｂ１１ｓｃＦｖ能与ＨＲＰＣＯＣ１６６９卵巢癌单抗反应并与卵巢癌抗原共同竞争结合卵巢癌单抗ＣＯＣ１６６９，抑制率达６７％，Ｗｅｓｔｅｒｎｂｌｏｔ显示其相对分子质量为２８×１０４，证明纯化后的表达蛋白质，能模拟卵巢癌抗原与卵巢癌单抗特异结合。结论：以包涵体表达的６Ｂ１１ｓｃＦｖ，经溶解复性纯化后，纯度高，活性好。

Objective: To study the renaturation, purification and binding activity of 6B11 ovarian carcinoma anti idiotypic antibody scFv expressed as inclusion bodies in E. coli . Methods: Inclusion bodies collected after the breakage of bacteria through sonication were subjected to repeatedly washing. Inclusion bodies solubilized in the presence of 8 mol·L -1 urea were diluted with renaturation solutions so that folding process could be initiated. The renaturation conditions were optimized including time, temperature and oxidized glutathione (GSSG) and reduced glutathione (GSH) concentration, respectively. 6B11scFv renatured proteins were purified on DEAE Sepharose Fast Flow ion exchange column with salt gradient elution. The purity was examined by SDS PAGE. The binding activities were determined by Western blot, ELISA and inhibition ELISA, separately. Results: By means of DEAE Sepharose Fast Flow, 6B11scFv proteins were obtained with a purity of over 95%. The optimum conditions were 5 mmol·L -1 and 0.5 mmol·L -1 for the concentrations of GSSG and GSH, respectively, and renatured time more than 48 hours at 10 ℃. The expressed proteins after purification could specifically react with the primary anti ovarian carcinoma monoclonal antibody (COC166 9). Inhibition rate could reach 67% by inhibition ELISA. Western blot showed that tested protein could react with COC166 9 that appeared at 2.8×10 4, i.e. the purified protein could mimic