Center for Advanced Technology, Adam Mickiewicz University, Uniwersytetu Poznanskiego 10, 61-614 Poznan, Poland.
Faculty of Chemistry, Adam Mickiewicz University, Uniwersytetu Poznanskiego 8, 61-614 Poznan, Poland.
Int J Mol Sci. 2021 Apr 30;22(9):4773. doi: 10.3390/ijms22094773.
Within the reactive oxygen species (ROS) generated by cellular metabolisms, hydroxyl radicals (HO) play an important role, being the most aggressive towards biomolecules. The reactions of HO with methionine residues (Met) in peptides and proteins have been intensively studied, but some fundamental aspects remain unsolved. In the present study we examined the biomimetic model made of Ac-Met-OMe, as the simplest model peptide backbone, and of HO generated by ionizing radiation in aqueous solutions under anoxic conditions. We performed the identification and quantification of transient species by pulse radiolysis and of final products by LC-MS and high-resolution MS/MS after γ-radiolysis. By parallel photochemical experiments, using 3-carboxybenzophenone (CB) triplet with the model peptide, we compared the outcomes in terms of short-lived intermediates and stable product identification. The result is a detailed mechanistic scheme of Met oxidation by HO, and by CB triplets allowed for assigning transient species to the pathways of products formation.
在细胞代谢产生的活性氧 (ROS) 中，羟基自由基 (HO) 起着重要作用，对生物分子的攻击性最强。HO 与肽和蛋白质中的蛋氨酸残基 (Met) 的反应已经得到了深入研究，但一些基本方面仍未得到解决。在本研究中，我们检查了由 Ac-Met-OMe 组成的仿生模型，该模型是最简单的肽骨架，以及在缺氧条件下通过电离辐射在水溶液中产生的 HO。我们通过脉冲辐射解法鉴定和定量了瞬态物种，并通过 LC-MS 和高分辨率 MS/MS 对 γ 辐照后的终产物进行了鉴定。通过平行光化学实验，使用模型肽的 3-羧基二苯甲酮 (CB) 三重态，我们比较了短寿命中间体和稳定产物鉴定方面的结果。结果是 HO 和 CB 三重态氧化 Met 的详细机制方案，允许将瞬态物种分配到产物形成途径中。
