中文摘要：

通过筛选牛蛙皮肤cDNA文库得到牛蛙凝集素Catesbeianalectin，相对分子质量仅为1465．8，是目前已知的相对分子质量最小的凝集素，且具有很强的凝集红细胞及病原细菌作用。利用CD检测牛蛙凝集素的二级结构为典型的PPⅡ螺旋。为了探究牛蛙凝集素Catesbeianalectin的体内组织靶向性分布规律，对其进行了放射性同位素^125I标记，通过尾静脉注射、腹腔注射及灌胃3种方式给药，并于随后进行既定时间点动态显像、采血及各组织中放射性强度的测量。同位素标记Catesbeianalectin的标记率为97．3％，放化纯度为99．3％，在体外和体内模拟试验中具有良好的稳定性和理想的体内分布特征。采用尾静脉注射^125I-Catesbeianalectin时，肝脏、脾脏和肺脏中放射性凝集量最高，且主要通过肝脏代谢；采用灌胃及腹腔注射^125I-Catesbeianalectin时，胃及脾脏中放射性凝集量最高且，主要通过胃代谢；3种途径给予^125I-Catesbeianalectin后，均不能通过血脑屏障，静脉注射是该药物较好的给药途径，为进一步研究牛蛙凝集素Catesbeianalectin的靶向载体作用提供基础。

英文摘要：

Catesbeianalectin was screened from the cDNA library of Rana Catesbeiana skin, the relative molecular quality was only 1 465.8,which was currently the smallest known lectin,which had strong agglutination with red blood cells and pathogenic bacteria. The CD detection showed the secondary structure was typical PP Ⅱ helix. Catesbeianalectin was labeled by ^125I aimed to research the tissue biodistribution in vivo ,intravenous（i. v. ）,intraperitoneal（i. p. ） and irrigate（i, g. ） administration routeg of ^125I-Catesbeianalectin at an equal radiation dose at the designated time points dynamic bioimagings were performed, blood samples were collected before sacrifice and the amounts of radioactivity in tissue samples were measured. The results revealed that the labeling rates and radiochemieal purities of the ^125I-Catesbeianalectin were 97.3% and 99.3% ,and was apparently stable in mice plasma that could improve its bioavailability and suitable in vivo distribution. Catesbeianalectin was proved to mainly accumulate in liver,spleen and lung after i. v. and delivery in liver, mainly accumulate in stomach and spleen after i. p. and i. g. and delivery in stomach.Any of the three administration routes of ^125I-Catesbeianalectin could not pass the blood brain barrier,and intravenous injection was the preferred administration route of the lectin, the research provided the basis for further research on bullfrog lectin Catesbeianalectin targeting vector.