中文摘要：

目的研究化学修饰剂聚乙二醇（PEG）对德国小蠊（蟑螂）重组变应原rBlag2变应原性的影响。方法rBlag2在大肠肝菌中表达后，采用Ni^＋亲和层析纯化，然后甲氧基聚乙二醇2．N-羟基琥珀酰亚胺酯（mPEG2-NHS，Mr为10×10^3）修饰，经阳离子交换层析纯化，用SDS．PAGE、免疫印迹及ELISA分析其生物学特性。结果rBlag2纯化后的相对分子质量（肘，）约39×10^3；SDS-PAGE分析PEG-rBlag2修饰产物，考马斯亮蓝染色可呈现5条带，而I2-KI染色则呈现7条带。对修饰产物的纯化表明阳离子交换层析可分离rBlag2和PEG-rBlag2；对修饰产物的免疫印迹分析显示恤为100×10^3和130×10^3的修饰带可与蟑螂过敏患者血清特异性IgE结合，同时ELISA分析结果表明PEG-rBlag2复合物的体外免疫学反应性显著下降，仅为原来的42％。结论PEG修饰可保持rBlag2与特异性抗体结合能力，却大大降低变应原的体外免疫学反应性，为重组低致敏原的研究提供了基础资料。

英文摘要：

Objective To research the effect of PEGylation on rBla g 2 from Blattella germanica. Methods rBla g 2 allergen expressed in E. coli was purified by Ni^＋ affinity chromatography, then was PEGylated by mPEG2-NHS（Mr,10 ×10^3）. The PEG-rBla g 2 was purified by CM-Sepharose, a cation exchange chromatography. SDS-PAGE, Western blot and ELISA were used to characterize its biological activity. Results The relative molecular mass of the purified rBla g 2 was about 39 ×10^3. PEG-rBla g 2 was analyzed by SDS-PAGE. Five bands were visualized by staining with Coomassie Brilliant Blue R-250, while seven bands by staining with I2-KI. Cation exchange chromatography could separate rBla g 2 and PEG-rBla g 2. The 100 ×10^3（Mr） and 130 ×10^3（Mr） of PEG-rBla g 2 could combined with the special IgE from sera of one cockroach-allergic patient by Western blot. The immunological activities of PEG-rBla g 2 in vitro decreased remarkably by ELISA, which was only 42% of rBla g 2. Conclusion PEGylated allergen can retain the ability of combining with special IgE from sera, while its immunological activities reduce enormously, which establishes the basic work of researching recombinant low-sensitive allergens.