蛇毒PLA2家族具有出血毒、神经毒、心脏毒、抗血小板聚集等毒性，是蛇毒中的主要毒素。因此，PLA2抑制剂可以有效降低毒蛇咬伤的致死致残率，是除抗蛇毒血清之外的良好抗蛇伤药。天然的PLA2抑制蛋白主要来自蛇本身，它是与蛇毒协同进化的产物。通过筛选，我们前期在华游蛇中发现了一种可强烈抑制蛇毒PLA2酶活性和出血毒性的蛋白-PLIγ。我们还发现PLIγ在多种蛇肝脏均有表达，但活性差异较大。为了深入了解PLIγ结构与功能的关系，我们拟采用DNA改组、易错PCR和DNA定点突变等方法，对华游蛇PLIγ进行分子改造，利用噬菌体表面展示技术，筛选更强抑制活性的PLI γ突变体。我们还将通过生物信息学方法，分析高活性PLIγ的二级和空间结构特点，进一步明确PLIγ的关键氨基酸和结构域。基于这些位点和结构域，通过分子对接和活性实验，我们希望得到强活性PLIγ小分子模拟肽，为抗蛇毒和抗炎性疾病药物奠定基础。

Snake venom phospholipase A2s exhibit a wide range of physiopathological effects, including haemorrhagin, neurotoxicty, cardiotoxicity, and anti-aggregation of platelet, etc., and is known as the major toxin. Therefore, inhibitors of PLA2 are able to diminish the mortality and morbidity of snake envenomation, and are considered as potential antivenom candidate besides antivenin. Natural PLA2 inhibitor (PLI) proteins are mainly found in snake species as product of co-evolution with venom. In our previous assays, we discovered a new gamma PLI from Sinonatrix annularis that strongely inhibited enzymatic and hemorrhagic acitivities of svPLA2. What's more, PLIγ were expressed in a variety of snake livers, but differed in acitivities. In order to investigate the structure-function relationship, we schemed to modify the PLIγ molecule of Sinonatrix annularis by DNA shuffling, error-prone PCR and site-specific mutagenesis. Phage display technique are going to be used to screen PLIγ mutations that with higher inhibition effeciency. Bioinformation analysis on these high acitivity PLIγs' secondary and 3D structure will be carried out for a further understanding of key amino acids and domains. Subsequently, mimic peptides design and validation will be conducted by employing molecular docking and assay. These experiments are benificial to drug discovery of antivenom and anti-inflammation diseases.