羟基自由基介导的离体DNA中8-羟基鸟嘌呤的形成。

Hydroxyl free radical mediated formation of 8-hydroxyguanine in isolated DNA.

作者信息

Floyd R A, West M S, Eneff K L, Hogsett W E, Tingey D T

机构信息

Oklahoma Medical Research Foundation, Oklahoma City 73104.

出版信息

Arch Biochem Biophys. 1988 Apr;262(1):266-72. doi: 10.1016/0003-9861(88)90188-9.

DOI:10.1016/0003-9861(88)90188-9

PMID:2833169

Abstract

Formation of 8-hydroxyguanine within calf thymus DNA has been studied after exposure to uv-H2O2 as a hydroxyl free radical generating system. Using high-pressure liquid chromatography with electrochemical detection, we measured the amount of 8-hydroxy-2-deoxyguanosine (8-OHdG) in the enzymatically digested DNA. The 8-OHdG content of uv-exposed DNA increased linearly with increasing H2O2 levels up to 0.03%, above which the rate of increase was less than linear. All hydroxyl free radical scavengers studied (mannitol, ethanol, thiourea, and salicylate), if present in the system when DNA was exposed to uv-H2O2, caused a decrease in the amount of 8-OHdG formed. Thiourea when incubated with damaged DNA caused a loss of 8-OHdG when it was an integral part of DNA. In contrast, thiourea did not react with the nucleoside free in solution. Reduced glutathione did not cause a decrease of 8-OHdG, either when it was an integral part of DNA, or, as the free nucleoside in solution.

摘要

在将紫外光-H₂O₂作为羟基自由基产生系统暴露于小牛胸腺DNA后，对其中8-羟基鸟嘌呤的形成进行了研究。使用配备电化学检测的高压液相色谱法，我们测量了经酶消化的DNA中8-羟基-2-脱氧鸟苷（8-OHdG）的含量。紫外线照射的DNA中8-OHdG的含量随H₂O₂水平的增加呈线性增加，直至0.03%，超过该水平后增加速率低于线性。所研究的所有羟基自由基清除剂（甘露醇、乙醇、硫脲和水杨酸盐），如果在DNA暴露于紫外光-H₂O₂时存在于系统中，都会导致形成的8-OHdG量减少。硫脲与受损DNA一起孵育时，当它是DNA的组成部分时会导致8-OHdG损失。相比之下，硫脲不与溶液中游离的核苷发生反应。还原型谷胱甘肽无论是作为DNA的组成部分，还是作为溶液中的游离核苷，都不会导致8-OHdG减少。