ELECTRON GAIN AND ELECTRON LOSS RADICALS STABILIZED ON THE PURINE AND PYRIMIDINE OF A COCRYSTAL EXHIBITING BASE BASE INTERSTACKING - ESR-ENDOR OF X-IRRADIATED ADENOSINE-5-BROMOURACIL
ELECTRON GAIN AND ELECTRON LOSS RADICALS STABILIZED ON THE PURINE AND PYRIMIDINE OF A COCRYSTAL EXHIBITING BASE BASE INTERSTACKING - ESR-ENDOR OF X-IRRADIATED ADENOSINE-5-BROMOURACIL
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DOI：
10.2307/3575980
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发表时间：
1983-01-01
影响因子：
3.4
通讯作者：
BERNHARD, WA
中科院分区：
文献类型：
--
作者：
KAR, L;BERNHARD, WA
捕获在腺苷：5-溴尿嘧啶的共晶体中的主要自由基在12 ° X-照射。K通过ESR-ENDOR [电子核双共振]光谱法鉴定，并在退火至480 ℃后进行自由基反应。K.主要的电子夺取和电子加成产物在12 ℃下稳定在碱上。K被观察到是溴尿嘧啶π。阳离子和腺嘌呤.阳离子和π-的阴离子溴尿嘧啶上阴离子的形成是由在较高温度下氘加成到溴尿嘧啶的C6上形成的自由基推断的。40度以上。K溴尿嘧啶. pi. -阳离子似乎通过复合而衰减，并在约x时降低到不可检测的水平。170.degree. K.两个腺嘌呤. π-还观察到离子在相同的温度范围内衰减。200度以上。K氢加合物稳定在碱上。使用部分氘代共晶的实验表明，H-加合物是通过H加成和相应阴离子的质子化形成的。在高于200 ℃的温度下，可检测到稳定在糖残基上的两个H提取自由基。K，但这些可能存在于低得多的温度下。在嘌呤：嘧啶堆积相互作用的存在下，空穴主要转移到嘌呤，而电子主要转移到嘧啶。
The predominant free radicals trapped in cocrystals of adenosine:5-bromouracil X-irradiated at 12.degree. K were identified by ESR-ENDOR [electron nuclear double resonance] spectroscopy and the radical reactions were followed upon annealing to 480.degree. K. The dominant electron abstraction and electron addition products stabilized on the bases at 12.degree. K are observed to be the bromouracil .pi.-cation and the adenine .pi.-cation and .pi.-anion. The formation of an anion on bromouracil is inferred from the presence of a radical formed by deuterium addition to C6 of bromouracil at higher temperatures. Above 40.degree. K the bromouracil .pi.-cation appears to decay by recombination and is reduced to undetectable levels at .apprx. 170.degree. K. Both adenine .pi.-ions are also observed to decay within the same temperature range. Above 200.degree. K hydrogen adducts are stabilized on the bases. Experiments using partially deuterated cocrystals indicate that the H-adducts are formed via both H addition and protonation of the respective anions. Two H abstraction radicals stabilized on the sugar residue are detectable at temperatures above 200.degree. K, but these may be present at much lower temperatures. In the presence of purine:pyrimidine stacking interactions, holes are predominantly transferred to the purines while electrons are predominantly transferred to the pyrimidines.