【作者】 赵丹；

【导师】 谢达平；

【作者基本信息】 湖南农业大学 ， 生化与分子生物学， 2005， 硕士

【摘要】 蓖麻毒蛋白Ricin是存在于蓖麻种子中的一种毒蛋白,分子量在64 000,由A,B两条肽链基组成,通过二硫键相连。A链是活性链,分子量在31 000,B链分子量在34 000,具有凝集素活性,能与半乳糖残基结合。A链通过B链特异地结合细胞表面的受体,通过经受体介导的内吞方式进入细胞。A链能与核糖体的60S大亚基结合,通过其特异的N-糖苷酶活性,催化切断60S亚基28S rRNA中第4234位腺嘌呤与核糖分子之间的糖苷键,这一嘌呤的脱落可导致整个核糖体的失活,从而影响需核糖体参与的氨基酰-tRNA的结合和肽酰-tRNA的转位过程,最终导致蛋白质合成障碍,引起细胞的死亡。蓖麻毒素具有强烈的细胞毒性,因此具有抗肿瘤和开发生物农药的前景。 本文研究了从蓖麻种子中分离纯化蓖麻毒蛋白的方法,对蓖麻籽粗提物和蓖麻毒蛋白进行了杀虫研究。经硫酸铵盐析,亲和层析和凝胶过滤,得到了纯的蓖麻毒蛋白,在SDS-PAGE中,显示出分子量在64 000左右,存在两个亚基,分子量分别为31 000和34 000,与文献报道相符合。用蓖麻籽粗提物和毒蛋白对蚜虫和菜青虫进行毒力测定,结果表明,蓖麻毒蛋白具有一定的触杀毒性,对菜青虫胃毒活性弱,蓖麻碱具有较强的胃毒,触杀活性,并对菜青虫具有较高的拒食活性。更多还原

【Abstract】 The ricin is a plant toxin that can be isolated from castor beans (Ricinus communis). The protein toxin has a molecular weight of about 64 000, which consists of two chains linked by a disulfide bond. Ricin A chain (RTA) is a ribosome-inactivating protein, whose molecular weight is about 31 000. Ricin B chain is the binding subunit and can specifically recognize receptors on the cell membrane, which have a terminal galactose. RTB molecular weight is about 34 000. The ricin enters into the cell through receptor-mediated endocytosis. RTA binds to protein L3 of ribosomal 60S subunit. It has specific N-glycosidase activity, and can catalytically cleave a specific adenine at the site of 4 234 out of the 28S rRNA. This cleavage of adenine can lead to the disruption of ribosomal function, thereby, inhibits the protein synthesis, and then cause the death of cells. For this reason, ricin has a good future for applying on anti-tumor and biological pesticide.Experimental methods and technology for the separation and purification of ricin from castor beans were described in this paper. By ammonium sulfate precipitation, Sepharose-4B affinity chromatography, and followed by molecular sieve chromato -graphy, purified ricin was obtained. The purified preparation showed two protein bands with relative molecular weights of 31 000 and 34 000. Effects of ricin and castor beans’ raw extract against Pieris rapae (Linnaeus) larva and Myzws Persicae (Sulzer) were tested.The result showed that the ricin has a effect of contact toxicity on Pieris rapae (Linnaeus) larva, and it has few stomach toxicity effect. The ricinine has strong stomach and contact toxicity, and it also has strong antifeeding action against Pieris rapae (Linnaeus) larva.更多还原