The alkoxy radical, RCH2Ȯ, as a free radical product in x‐irradiated single crystals of nucleosides and nucleotides
The alkoxy radical, RCH2Ȯ, as a free radical product in x‐irradiated single crystals of nucleosides and nucleotides
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烷氧基，RCH2ş，作为 x 辐照的核苷和核苷酸单晶中的自由基产物
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
H. Zehner
中科院分区：
文献类型：
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作者：
W. Bernhard;D. Close;J. Hüttermann;H. Zehner
在X射线照射的3′-胞苷酸（3′CMP）、5-氯脱氧尿苷（ClUdR）、5-溴脱氧尿苷（BUdR）、腺苷盐酸盐（AR HCl）和脱氧腺苷一水合物（AdR <$H2O）中，由于伯羟基的O 5 ′的氢净损失而形成RCH 2 O自由基。在78 ~ 100 K温度范围内对3′CMP、ClUdR、BUdR和AR·HCl单晶和AdR·H2O多晶进行了ESR测量。主g值的范围为gmax=2.054-2.093，gint=2.005-2.009，gmin =1.995-2.000。各向同性β-氢超精细耦合的总和范围为Aβ 1 iso +Aβ 2 iso =141-156 G。g张量和Aβiso值被用来确定哪一个氧非键轨道包含了大部分的未成对电子密度。未成对电子2 p轨道对称轴垂直于由X（H）确定的平面。在未受损的分子中的两个相关氢键中，X-H键保持完整，而O-H键中的氢被取代。方程Aβiso= B 0 +B2 cos 2 θ，其中B 0 =0，
The RCH2Ȯ radical is formed in x‐irradiated 3′‐cytidylic acid (3′CMP), 5‐chlorodeoxyuridine (ClUdR), 5‐bromodeoxyuridine (BUdR), adenosine⋅HCl (AR⋅HCl), and deoxyadenosine monohydrate (AdR⋅H2O) owing to the net loss of hydrogen from O5′ of the primary hydroxylic group. ESR measurements were made between 78 and 100 K on single crystals of 3′CMP, ClUdR, BUdR, and AR⋅HCl and on polycrystalline AdR⋅H2O. The range of principal g values is gmax=2.054–2.093, gint=2.005–2.009, gmin =1.995–2.000. The range of sum of the isotropic β‐hydrogen hyperfine couplings is Aβ1iso +Aβ2iso=141–156 G. The g tensors and Aβiso values are used to determine which oxygen nonbonding orbital contains the bulk of the unpaired electron density. The unpaired electron 2p orbital symmetry axis is perpendicular to a plane determined by X(H) ⋅⋅⋅Ȯ–C. Of the two relevant hydrogen bonds in the undamaged molecule, the X–H⋅⋅⋅O bond remains intact whereas the hydrogen in the O–H⋅⋅⋅Y bond is displaced. The equation Aβiso=B0+B2 cos2ϑ, with B0 =0 an...