聚乙二醇修饰的蓖麻毒蛋白A链的特性研究

Study on the properties of Ricin A-chain modified by polyethylene glycol

目的:研究两种不同相对分子质量(Mr)的单甲氧聚乙二醇(Monomethoxy polyethylene glycol,mPEG)与蓖麻毒蛋白A链(ricin A-chain,RTA)偶联后三者的免疫原性和毒性的不同。方法:从天然蓖麻籽中提取纯化的RTA,并分别与相对分子质量为5KD和10KD的mPEG反应偶联,得到两种不同的RTA-mPEG偶联物。用蛋白质印迹方法比较RTA和不同的RTA-mPEG偶联物之间的免疫原性的变化,此外通过用噻唑蓝比色法(MTT)对RTA及不同偶联物的体外细胞毒性进行评价,并通过测定半数致死量(LD50)的方法比较它们的体内毒性。结果:经聚乙二醇修饰后的RTA,其毒性有明显的下降。此外,对其免疫原性的研究表明,RTA的PEG化也能降低RTA的免疫原性。结论:聚乙二醇能遮蔽RTA,使其免疫原性和毒性有很大的降低。且下降的程度同与RTA偶联的聚乙二醇的相对分子量成正相关。

OBJECTIVE To study the difference in immunogenicity and toxicity of ricin A-chain（RTA） and RTA-mPEGs.METHODS RTA and PEG-RTA conjugates modified by polyethylene glycol （PEG） with different MW （5 000 and 10 000） were prepared. The irnmunogenicity of RTA and RTA-mPEG was compared by Western blot method. The in vivo and in vitro toxicity was compared by the determination of LD50 and MTT method respectively. RESULTS The immunogencity and toxicity of RTA modified by mPEG were reduced remarkably. （3ONCLUSlON Immunogenicity and toxicity of RTA-mPEG decrease significantly compared with free RA probably as PEG can cover RTA. The decreasing txtent is proportional to molecular weight of the PEG.