镉暴露家兔睾丸和肝脏中小分子金属结合蛋白的分离与比较  

Isolation and Comparison of Low-Molecular-Weight Metal Binding Protein in Testis and Liver of Rabbits Treated with Cadmium

作　　者：卞建春 郭恒杰[1] 王捍东[1] 刘学忠[1] 袁燕[1] 任建新[1] 刘宗平[1] 王宗元[1] 康世良[2] 武瑞[3] 

机构地区：[1]扬州大学兽医学院,江苏扬州225009 [2]东北农业大学动物医学院,哈尔滨150030 [3]黑龙江八一农垦大学动物医学院,黑龙江大庆163319

出　　处：《中国农业科学》2009年第3期1091-1099,共9页Scientia Agricultura Sinica

基　　金：国家自然科学基金项目(39870567)

摘　　要：【目的】通过对镉暴露家兔睾丸和肝脏中小分子金属结合蛋白分离与比较,揭示动物睾丸组织镉高敏感性的机制。【方法】6月龄雄性青紫兰家兔经皮下染镉,9d后将兔子杀死,制备睾丸和肝脏匀浆超离上清液,用Sephadex G-75凝胶层析法进行蛋白分离,经双波长(280nm和254nm)测定紫外吸收和原子吸收分光光度法测定Cd、Zn元素含量两种方法确定洗脱液小分子量金属结合蛋白峰管;通过试验比较它们的紫外扫描特性、热稳定性、镉锌元素比值和氨基酸组成。【结果】肝脏分离蛋白分子量为6.0～10.0kD,有254nm特征紫外吸收峰,OD250nm/OD280nm的值为13.13,有较好的热稳定性,不被无水乙醇抽提,每摩尔物质中Cd与Zn的摩尔比为4.7﹕2,半胱氨酸相对比例为32.89%、不含芳香族氨基酸、氨基酸组成与MT的理论值非常接近。睾丸分离蛋白无254nm特征紫外吸收峰,Cd结合能力低,半胱氨酸相对含量只有2.36%,氨基酸组成与MT的理论组成相差较大。【结论】雄性动物睾丸对镉暴露敏感性高的原因是睾丸中不能被诱导产生能够拮抗重金属镉毒性作用的特殊蛋白质——金属硫蛋白。[ Objective] To isolate and compare the small molecular weight proteins in liver and testes of rabbits challenged by cadmium to recognize the mechanism of sensitivity of testes against cadmium. [ Method ] Ten male Chinchilla rabbits at the age of 6-month-old were injected subcutaneously by cadmium at different doses, nine days later, the animals were killed, livers and testes of the rabbits were removed and iced at --70℃. Livers and testes were minced and homogenized and ultracentrifugated, the supernatant of livers and testes were collected, respectively, and a part of supematant were passed a column with Sephadex G-75 and the column was calculated by marker. The wash solution from column were fractioned, proteins in each tube were measured by ultraviolet scanning, and cadmium and zinc in tubes were measured by atomic absorption spectrophotometry. [Result] There was a peak of protein in liver supematant induced by cadmium measured at 254nm. The molecular weight of the protein within the peak was 6.0-10.0 kD, and heat-stable, cysteine was rich, could not be extracted by alcohol, no aromatic amino acid in the protein. The ratio of Cd/Zn was 4.7：2. The components of this protein was much similar as metallothionein. However, there was no peak of testis supernatant measured at 254nm, and no similar protein in testis supernatant of animals dosed by cadmium. [Conclusion] The reason of male rabbit testes are sensitive to cadmium challenge is that tastes can not produce matallothionein which can against heavy metals from damage.

关 键 词：睾丸 肝脏 镉 敏感性 金属硫蛋白 

分 类 号：X174[环境科学与工程—环境科学]