METHYLENE-BLUE PLUS LIGHT MEDIATES 8-HYDROXYGUANINE FORMATION IN DNA
METHYLENE-BLUE PLUS LIGHT MEDIATES 8-HYDROXYGUANINE FORMATION IN DNA
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DOI：
10.1016/0003-9861(89)90167-7
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发表时间：
1989-08-15
影响因子：
3.9
通讯作者：
SCHNEIDER, JE
中科院分区：
文献类型：
--
作者：
FLOYD, RA;WEST, MS;SCHNEIDER, JE
暴露在亚甲基蓝(MB)加光线下，DNA中会形成大量的8-羟基鸟嘌呤。DNA中存在的8-羟基-2‘-脱氧鸟苷(8-OHdG)的量在所研究的2到200微米范围内随着MB浓度的增加而增加，并且依赖于光照射。随着光照时间的增加，当MB为200µm时，光照15分钟后8-OHdG的含量也增加到约750 8-OHdG/105脱氧鸟苷的水平。尽管先前的研究表明，来自各种来源的羟基自由基介导了DNA中8-OHdG的形成，但MB+光实验中的甘露醇、超氧化物歧化酶、过氧化氢酶和去铁醛的存在证明，这些氧自由基中间体或前体的清除剂要么没有引起MB+光暴露的DNA中8-OHdG含量的变化，要么增加了DNA中8-OHdG的含量。这些结果似乎排除了氧自由基中间体在MB加光介导的DNA中8-OHdG形成的主要事件中的直接作用。氧气是导致亚甲基蓝加光在DNA中形成8-OHdG所必需的。我们注意到，当氧化重水的含量增加到100%时，DNA中8-OHdG的生成量比在纯H2O中进行类似反应时增加了约三倍。使用单线态氧清除剂2，5-二甲基呋喃对MB加光介导的DNA中8-OHdG的形成产生了不同的结果。集体获得的数据清楚地表明，MB+LIGH介导了DNA中8-OHdG的形成。D2O数据和对氧的需求表明，单线态氧可能是一种中间体。
Exposure to methylene blue (MB) plus light mediates formation of large levels of 8-hydroxyguanine in DNA. The amount of 8-hydroxy-2''-deoxyguanosine (8-OHdG) present in DNA increased as the amount of MB concentration increased throughout the 2 to 200 .mu.M range studied and was dependent on light exposure. As the time of light exposure increased so did the 8-OHdG content to levels of about 750 8-OHdG/105 deoxyguanosine after 15 min of light exposure when MB was at 200 .mu.M. Even though previous research has demonstrated that hydroxyl free radicals formed from a variety of sources mediate 8-OHdG formation in DNA, inclusion of mannitol, superoxide dismutase, catalase, and desferal in the MB plus light experiments demonstrated that these scavengers of oxygen free radical intermediates or precursors caused either no change or an increase in the 8-OHdG content of DNA exposed to MB plus light. These results appear to rule out the direct role of oxygen free radical intermediates in the primary events involved in the MB plus light mediated formation of 8-OHdG in DNA. Oxygen was essential to cause MB plus light mediated 8-OHdG formation in DNA. It was noted that when the reaction was carried out where the deuterium oxide content had been increased to 100%, the amount of 8-OHdG formed in DNA increased about threefold over that observed when comparable reactions were carried out in pure H2O. Use of the singlet oxygen scavenger 2,5-dimethylfuran has yielded variable results on the MB plus light mediated formation of 8-OHdG in DNA. The data taken collectively clearly indicate that MB plus light mediates 8-OHdG formation in DNA. The D2O data and the requirement for oxygen suggest that singlet oxygen may be an intermediate.