中文摘要：

通过筛选牛蛙皮肤cDNA文库得到具有较强抗菌抗肿瘤活性肽Catesbeianin-1a,合成其成熟肽氨基酸序列,MIC法测定抑菌活性结果表明,Catesbeianin-1a对临床常见的致病菌具有较强的抑菌活性,其中对猪链球菌2型的MIC为2.5mg/L,且对兔红细胞几乎无溶血性。MTT法测定多肽抗肿瘤细胞活性,结果 Catesbeianin-1a对胃癌细胞和肝癌细胞的抑杀活性很强,对肝癌细胞SGC7901的IC50为0.845mg/L。制作透射电镜超薄切片,利用透射电镜观察活性肽对细菌和肿瘤细胞超微结构的影响,旨在初步探讨牛蛙皮肤活性肽Catesbeianin-1a抗菌、抗肿瘤的作用机制,并以Catesbeianin-1a为基础进行分子改造来提高其抗肿瘤的靶向性并降低其毒性。

英文摘要：

By screening the cDNA library of Rana catesbeiana,a novel bio-active peptide Catesbeianin-la with strong antibacterial activity and anti-tumor activities was obtained.The antibacterial activities was detected by minimum inhibitory concentration（MIC）methods,and the results showed that Catesbeianin-la had stronger inhibition activities to Streptococcus suis type 2,with MIC 2.5mg/L.The Catesbeianin-la hardly has any hemolytic activity to rabbit erythrocyte.The anti-tumor activity of Catesbeianin-la was assayed with MTT,The IC50 for hepatoma carcinoma cell strain SGC7901 was only 0.845 mg/L.In order to make some initial explore the anti-bacterial and anti-tumor mechanism of Catesbeianin-la,the influences of Catesbeianin-la on the tumor ultrastructure were observed by transmission electron microscope.This study provided a basis of the studying of the diversity of bioactive peptides of amphibians,developing of new antibiotic or anticancer drugs,and the designing of new type bioactive peptide with low cytotoxicity.