中文摘要：

目的应用噬菌体展示免疫球蛋白（Ig）结合分子组合文库，进化筛选获得与兔IgG结合的代表性序列，测定其与兔IgG及人IgG结合活性的差异，以判断筛选获得的代表性序列对不同种属Ig的结合是否存在倾向性的差别。方法应用包含Ig效应子结合蛋白Protein A的D结构域（PA-D）、A结构域（PA-A），ProteinG的B2结构域（PG-B2）及protein L的B3结构域（PL-B3）的单结构域随机组合文库，以兔IgG对该组合文库进行进化筛选，序列比较分析筛选获得的代表性序列与人IgG进化筛选文库所得代表性序列的异同性；用ELISA和竞争抑制试验分别测定阳性噬菌体克隆与兔IgG及人IgG的结合活性。结果以免IgG经4轮分子进化筛选，获得在天然细菌蛋白中不存在的新的结构形式PA-A-PA-A，该结果与人IgG进化筛选所得代表性序列PA-A-PG有显著差异；兔IgG筛选序列PA-A-PA-A和人IgG筛选序列PA-A-PG分别显示出与兔Ig和人Ig结合力更强的特性。结论该研究首次应用噬菌体展示技术研究不同种属抗体效应子构象的不同，证实兔IgG和人IgG两者效应子构象之间确实存在差异。这一结论有助于阐明抗体效应子构象在不同种属之间的差异性。

英文摘要：

Objective To affinity select rabbit IgG （rIgG）-binding representative sequences from a combinatorial phage library displaying immunoglobulin （Ig）-binding molecules, and to evaluate whether the selected sequences exist tendency to different species by comparing the binding characteristics between the sequences binding to rIgG and to human IgG （hIgG）. Methods A combinatorial phage library which displayed randomly-rearranged variouspeptide-linked molecules of D and A domains of protein A, designated PA-D and PA-A respectively, B2 domain of protein G （PG-B2） and B3 domain of protein L （ PL-B3 ）, was used for evolutional selection with rlgG. The selected representative sequences were compared with those selected from the library with hIgG by sequencing analyses. Binding activities of positive phage clones binding to rIgG or hlgG were detected respectively by ELISA and competitive inhibition test. Results After four rounds of evolutional selection, a novel combinatorial molecule with characteristic structure of PA-A-PA-A, which didn＇t exist in natural bacteria Ig -binding molecules, was obtained in rIgG selection library. The sequence was a notable distinction with PA-A-PG that selected with hIgG. The tests showed that the sequence PA-A-PA-A selected with rlgG and the sequence PA-A-PG selected with hIgG have stronger combining power to rIgG and hlgG respectively. Conclusion Conformation of antibody effectors of different species was studied in this work for the first time by using phage display technology, and indicated that the conformational difference between rIgG effector and hIgG effector existed indeed. The results not only can be used to interpret conformational differences of antibody effectors of different species, but also could provide a powerful tool to further study the structure and functions of antibodies.