Timmins G S, Barlow G K, Silvester J A, Wei X, Whitwood A C
a Department of Chemistry , University of York , York , UK.
Redox Rep. 1997 Apr;3(2):125-33. doi: 10.1080/13510002.1997.11747099.
EPR spin-trapping, although a powerful, sensitive technique for the study of free radicals, can be susceptible to artefacts; one of the most intractable to determine has been the non-radical addition of a substrate to a spin-trap followed by oxidation of the product to an EPR-detectable nitroxide. This work details how differentially isotopically labelled spin-traps (either nitroso or nitrone) may be used to determine the presence (or absence) of such artefacts, and provide a semi-quantitative measure of the extent of their contribution to the total EPR spectra in spin-trapping reactions. Artefactual 'ene' addition of the nitroso spin-trap 3,5-dibromo-4-nitroso-benzenesulphonic acid (DBNBS) to tryptophan followed by oxidation to EPR-detectable products has been confirmed, as has its nucleophilic addition to the thiol of glutathione to give non-EPR detectable products. The nitrone α-phenyl-N-tert-butylnitrone (PBN) exhibited no such reactivity.
电子顺磁共振（EPR）自旋捕集技术虽然是研究自由基的一种强大且灵敏的技术，但可能容易受到假象的影响；其中最难确定的一种假象是底物非自由基加成到自旋捕集剂上，随后产物氧化为可通过EPR检测的氮氧化物。这项工作详细说明了如何使用同位素差异标记的自旋捕集剂（亚硝基或硝酮）来确定此类假象的存在（或不存在），并对它们在自旋捕集反应中对总EPR谱的贡献程度提供半定量测量。已证实亚硝基自旋捕集剂3,5 - 二溴 - 4 - 亚硝基苯磺酸（DBNBS）与色氨酸发生假象的“烯”加成，随后氧化为可通过EPR检测的产物，以及它与谷胱甘肽的硫醇发生亲核加成生成不可通过EPR检测的产物。硝酮α - 苯基 - N - 叔丁基硝酮（PBN）没有表现出这种反应性。
