ESR and ENDOR study of single crystals of L‐asparagine⋅H2O x‐irradiated at room temperature
ESR and ENDOR study of single crystals of L‐asparagine⋅H2O x‐irradiated at room temperature
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室温下 L-天冬酰胺·H2O x 辐照单晶的 ESR 和 ENDOR 研究
DOI：
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发表时间：
1977
期刊：
影响因子：
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通讯作者：
W. Bernhard
中科院分区：
文献类型：
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作者：
D. Close;George W. Fouse;W. Bernhard
本文研究了L-天冬酰胺H_2O和L-天冬酰胺D_2O单晶的ESR谱。由于这些数据显示了大量未分辨的超精细结构，因此进行了详细的ENDOR实验。ENDOR实验表明存在单个α-氢偶联。通过比较超精细耦合张量的主值（−33.4、−21.1、−10.7 G）的方向与各种可能的自由基模型所预期的等效方向，可以得出结论，在室温下L-天冬酰胺中观察到的主要自由基是CO（NH 2）<$HCH（N+H3）CO−2。通过详细的INDO计算，已适当地解释了ESR观察到的β-氢的ENDOR信号的缺乏和相当大的β-氮偶联（~ 5.0 G）的存在。
The ESR spectra of single crystals of L‐asparagine⋅H2O and L‐asparagine⋅D2O have been examined. Since these data show a great deal of unresolved hyperfine structure, a detailed ENDOR experiment was undertaken. The ENDOR experiment showed the presence of a single α‐hydrogen coupling. By comparing the directions of the principal values (−33.4, −21.1, −10.7 G) of the hyperfine coupling tensor with the equivalent directions expected from various possible free radical models, it was concluded that the dominant free radical observed in L‐asparagine⋅H2O at room temperature is CO(NH2) ĊHCH (N+H3)CO−2. The lack of an ENDOR signal from the β‐hydrogen and the presence of a rather large β‐nitrogen coupling (∼5.0 G) observed by ESR has been adaquately explained by a detailed INDO calculation.