铬(Ⅵ)-谷胱甘肽配合物诱导DNA构象变化的作用机制  

Study on the Mechanism of DNA Conformation Change Induced by Cr(Ⅵ)-GSH Complex

作　　者：张文豪[1] 杨培慧[1] 

机构地区：[1]暨南大学化学系,广东广州510632

出　　处：《环境与健康杂志》2006年第3期221-224,共4页Journal of Environment and Health

基　　金：广东省自然科学基金资助项目(021190);广州市科技计划基金资助项目(2003Z3-D2041)

摘　　要：目的研究重铬酸钾和还原型谷胱甘肽(GSH)反应所形成的配合物与DNA的作用机制,了解Cr(Ⅵ)在体内的致癌过程。方法用1∶10的K2Cr2O7和GSH溶液形成Cr(Ⅵ)-GSH中间态配合物,配制1.4×10-3mol/L的DNA溶液,以溴化乙锭(EB)为DNA荧光探针,用紫外光谱、荧光光谱、Scatchard图及DNA热变性等方法研究Cr(Ⅵ)-GSH配合物对DNA构象变化的影响。结果在pH=7.4的4-(2-羟乙基)哌嗪乙磺酸(Hepes)缓冲溶液中,Cr(Ⅵ)与GSH反应后很快形成Cr(Ⅵ)-GSH中间态配合物。配合物与DNA不发生嵌插作用,也不与DNA磷酸骨架产生静电结合,而是在DNA碱基部位作用,破坏DNA二级结构。中间态配合物配合物不稳定,最终分解产物Cr(Ⅲ)可以和DNA进行交联,整个过程约1h进行完全。结论重铬酸钾和还原型谷胱甘肽(GSH)反应所形成的Cr(V)配合物在诱导DNA变性中起重要作用。Objective To study the interaction between Cr（Ⅵ）-GSH complex and DNA and to understand the mechanism of DNA conformation change induced by Cr（ Ⅵ ）-GSH complex. Methods Chromium（Ⅵ） reacts on glutathione forms the chromium （Ⅴ） intermediate complex, arid the intermediate complex can induce the conformation change of DNA, in the present paper, ultraviolet and fluoreseenee spectra, Seatchard equation, fluorescence quenching curve, and fluorescence probe method using ethidium hromide （EB） as a fluoreseenee probe were employed. Results The chromium （Ⅴ） intermediate complex formed rapidly after the reaetion between Cr（Ⅵ） and GSH in Hepes buffer solution at pH=7.4, the complex did not insert into the base pairs on the DNA duplex strand and developed electrostatic binding with the phosphate backbone of DNA, but induced a conformation change of DNA leading to a disruption of duplex structure. In the following time, the complex dec.omposed and the end produet was Cr（Ⅲ）, Cr（Ⅲ） can cross-link with DNA, the whole pmeess needs about an hour. Conclusion The chromium（Ⅴ） intermediate complex of the conformation change reaction of chromium（Ⅵ） and glutathione may play an important role in inducing the DNA.

关 键 词：DNA损伤 谷胱甘肽 重铬酸钾 荧光光谱 

分 类 号：R994.6[医药卫生—毒理学]