【摘要】 亚硝酸和NO.2 自由基被证明为致DNA突变因子 ,作为公认的氮原子中心的强氧化性亚硝基自由基NO.2 对DNA的作用引起为数众多的科学家的关注 ,但未观察到其直接作用的结果。利用脉冲辐解技术在碱性条件下观察到NO.2 直接氧化鸟嘌呤阴离子和鸟苷阴离子 ,并测定 pH1 2条件下NO.2 氧化鸟嘌呤阴离子反应的速率常数k =1 .3× 1 0 8dm3 mol-1s-1。但未观测到NO.2 与脱氧鸟苷 - 5 -磷酸及DNA的基他碱基的反应 ,说明NO.2 选择性氧化鸟嘌呤 ,糖基和磷酸根及其组成的链具有保护DNA不被NO.2 。氧化的作用更多还原

【Abstract】 Nitrogen doxide radical (NO\+.\-2) is known as a nitrogen centered free radical with powerful oxidizing properties. While ntric oxide and nitrous acid were prved to the able to cause mutation of DNA, the affect of NO\+.\-2 radical to DNA has being concerned by many scientists, but its direct result has not been observed. In this work, the reaction of NO\+.\-2 radical oxidizing guanine and guanosine in basic aqueous solution was observed directly by appoication of pulse radiolysis technique. Moreover, the rate constant of the reaction of NO\+.\-2 radical oxidizing guanine at pH 12, has been measured bo be k =1.3×10\+8. But to reaction about NO\+.\-2 radical with deoxyguanosine 5’-phosphate of other DNA bases was detected. It means that NO\+.\-2 radical is a selective radical to oxidize guaine, and that the glucoside, phosphate and their link of DNA take the protective action against oxidation by nitrogen dioxide radical更多还原