Chan Bun, Moran Damian, Easton Christopher J, Radom Leo
Graduate School of Engineering, Nagasaki University, Nagasaki, 852-8521, Japan.
School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia.
Chem Asian J. 2017 Jul 4;12(13):1485-1489. doi: 10.1002/asia.201700492. Epub 2017 May 23.
The tendency of peptides to be oxidized is intimately connected with their function and even their ability to exist in an oxidative environment. Here we report high-level theoretical studies that show that hydrogen bonding can alter the susceptibility of peptides to oxidation, with complexation to a hydrogen-bond acceptor facilitating oxidation, and vice versa, impacting the feasibility of a diverse range of biological processes. It can even provide an energetically viable mechanistic alternative to direct hydrogen-atom abstraction. We find that hydrogen bonding to representative reactive groups leads to a broad (≈400 kJ mol ) spectrum of ionization energies in the case of model amide, thiol and phenol systems. While some of the oxidative processes at the extreme ends of the spectrum are energetically prohibitive, subtle environmental and solvent effects could potentially mitigate the situation, leading to a balance between hydrogen bonding and oxidative susceptibility.
肽被氧化的倾向与其功能甚至其在氧化环境中存在的能力密切相关。在此，我们报告了高水平的理论研究，结果表明氢键可以改变肽的氧化敏感性，与氢键受体络合会促进氧化，反之亦然，这会影响多种生物过程的可行性。它甚至可以为直接氢原子提取提供一种能量上可行的机制替代方案。我们发现，在模型酰胺、硫醇和酚体系中，与代表性反应基团形成氢键会导致电离能出现宽泛（约400 kJ·mol）的光谱范围。虽然光谱两端的一些氧化过程在能量上是禁止的，但微妙的环境和溶剂效应可能会缓解这种情况，从而在氢键和氧化敏感性之间达成平衡。
