METHYLENE-BLUE PLUS LIGHT MEDIATES 8-HYDROXY 2'-DEOXYGUANOSINE FORMATION IN DNA PREFERENTIALLY OVER STRAND BREAKAGE
METHYLENE-BLUE PLUS LIGHT MEDIATES 8-HYDROXY 2'-DEOXYGUANOSINE FORMATION IN DNA PREFERENTIALLY OVER STRAND BREAKAGE
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DOI：
10.1093/nar/18.3.631
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发表时间：
1990-02-11
影响因子：
14.9
通讯作者：
FLOYD, RA
中科院分区：
文献类型：
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作者：
SCHNEIDER, JE;PRICE, S;FLOYD, RA
亚甲基蓝(MB)加光，在氧气存在的情况下，在DNA中介导8-羟基鸟嘌呤的形成。8-羟基鸟嘌呤的产率可高达现有鸟嘌呤的2%至4%。结果表明，用亚甲蓝加光处理超螺旋DNA可产生单链刻痕。然而，单链划痕发生的频率大约是形成8-羟基鸟嘌呤的17倍。有镁离子存在时，划痕速率降低，但不能被铁催化的芬顿反应的抑制剂或羟基自由基的清除剂所阻止。在MB存在的情况下，将DNA广泛暴露在光下，不会产生可检测到的硫代巴比妥类活性物质，从而暗示单链划痕不会通过羟基自由基对脱氧核糖的攻击而发生。8-羟基鸟嘌呤的形成显然不依赖于MB与DNA的插层结合，因为它是在多脱氧鸟苷中形成的。
Methylene blue (MB) plus light, in the presence of oxygen, mediates formation of 8-hydroxyguanine in DNA. The yield of 8-hydroxyguanine may be as much as from 2 to 4% of the guanines present. The results presented here show that treatment of supercoiled plasmid DNA with methylene blue plus light causes single-stranded nicks. However, single-stranded nicking occurs approximately 17-fold less frequently than does formation of 8-hydroxyguanine. The nicking rate is reduced in the presence of Mg ion but is not prevented by inhibitors of the iron-catalyzed Fenton reaction or by scavengers of hydroxyl free radicals. Extensive exposure of DNA to light in the presence of MB produces no detectable thiobarbital reactive material thus implicating that single strand nicking does not occur by hydroxyl free radical attack on deoxyribose. Formation of 8-hydroxyguanine is apparently not dependent upon intercalative binding of MB to DNA, since it is formed in polydeoxyguanylic acid.