Evidence for intrastrand C2' hydrogen abstraction in photoirradiation of 5-halouracil-containing oligonucleotides by using stereospecifically C2'-deuterated deoxyadenosine
Evidence for intrastrand C2' hydrogen abstraction in photoirradiation of 5-halouracil-containing oligonucleotides by using stereospecifically C2'-deuterated deoxyadenosine
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DOI：
10.1016/0040-4039(96)00123-2
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发表时间：
1996-03-11
影响因子：
1.8
通讯作者：
Saito, I
中科院分区：
文献类型：
--
作者：
Sugiyama, H;Fujimoto, K;Saito, I
为了研究脱氧核糖C_1‘和C_2’H被尿酰-5-基抽提的性质，我们研究了六核苷酸d(GCA(B_R)UGC)(2)的光反应，其中一个脱氧核糖基的C_2‘氢被立体地专一性地去氢。与未标记的六聚体相比，(2‘R)-[2’-H-2]-2‘-脱氧腺苷六聚体(1)仅得到较少的8，而(2’S)-[2‘-H-2]-2’-脱氧腺苷六聚体(2)得到的8与未标记的六聚体基本相同。结果表明，C2‘氧化产物8的形成是通过尿酰-5-基对脱氧核糖部分的(2’α)-H进行限速提取而实现的。含U-Br-和U-I的六聚体光照射生成8的动力学同位素效应(k(H)/k(D))分别为7.5和7.2。
In order to investigate the nature of deoxyribose C1' and C2' H abstraction by uracilyl-5-yl radical in DNA, we have examined the photoreaction of hexanucleotides d(GCA(Br)UGC)(2) in which one of the C2' hydrogens of the deoxyribose moiety was stereospecifically deuterated. Irradiation of (2'R)-[2'-H-2]-2'-deoxyadenosine-containing hexamer (1) gave only a smaller amount of 8 compared to that of the unlabeled hexamer, whereas (2'S)-[2'-H-2]-2'-deoxyadenosine-containing hexamer (2) gave essentially the same amount of 8 as that obtained for the unlabeled hexamer. The results indicated that the formation of C2' oxidation product 8 occurs via a rate-limiting abstraction of (2'alpha)-H of the deoxyribose moiety by uracilyl-5-yl radical. The kinetic isotope effects (k(H)/k(D)) obtained for the formation of 8 by photoirradiation of U-Br- and U-I-containing hexamers were 7.5 and 7.2, respectively.