Radiation-Induced Radicals in Glucose-1-phosphate. I. Electron Paramagnetic Resonance and Electron Nuclear Double Resonance Analysis of in situ X-Irradiated Single Crystals at 77 K
Radiation-Induced Radicals in Glucose-1-phosphate. I. Electron Paramagnetic Resonance and Electron Nuclear Double Resonance Analysis of in situ X-Irradiated Single Crystals at 77 K
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DOI：
10.1021/jp804290e
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发表时间：
2008-11-27
影响因子：
3.3
通讯作者：
Callens, Freddy
中科院分区：
文献类型：
--
作者：
De Cooman, Hendrik;Vanhaelewyn, Gauthier;Callens, Freddy
电子磁共振分析的辐射诱导缺陷葡萄糖-1-磷酸二氢二钾单晶体在原位X射线照射和测量在77 K表明，至少有七个不同的碳为中心的自由基物种被困。其中四个（R1-R4）可以完全或部分地用质子超精细耦合张量来表征。主要的自由基（R2）被确定为C1-中心的物种，推测是由糖-磷酸连接的断裂和相邻C2碳上羰基的协同形成的。这种结构在化学上与最近在辐照过的蔗糖单晶中发现的一种自由基相同。自由基物种R1和R4最有可能分别是C3-和C6-中心的物种，两者都通过净氢提取形成。建议R3与R4化学上相似但几何上不同。在77 K存在的糖自由基的身份的知识提供了第一步，在阐明磷酰基自由基的形成机制之前检测到的X-照射后，在280 K。在论文II中，这些自由基物种的化学身份，精确的构象，和可能的形成机制进行了研究，通过DFT计算和基本洞察到糖和糖衍生物的辐射化学。
Electron magnetic resonance analysis of radiation-induced defects in dipotassium glucose-1-phosphate dihydrate single crystals in situ X-irradiated and measured at 77 K shows that at least seven different carbon-centered radical species are trapped. Four of these (R1-R4) can be fully or partly characterized in terms of proton hyperfine coupling tensors. The dominant radical (R2) is identified as a C1-centered species, assumedly formed by a scission of the sugar-phosphate junction and the concerted formation of a carbonyl group at the neighboring C2 carbon. This structure is chemically identical to a radical recently identified in irradiated sucrose single crystals. Radical species RI and R4 most likely are C3- and C6-centered species, respectively, both formed by a net hydrogen abstraction. R3 is suggested to be chemically similar to but geometrically different from R4. Knowledge of the identity of the sugar radicals present at 77 K provides a first step in elucidating the formation mechanism of the phosphoryl radicals previously detected after X-irradiation at 280 K. In paper II, the chemical identity, precise conformation, and possible formation mechanisms of these radical species are investigated by means of DFT calculations and elementary insight into the radiation chemistry of sugar and sugar derivatives is obtained.