Oxidative Damage in Aliphatic Amino Acids and Di- and Tripeptides by the Environmental Free Radical Oxidant NO<sub>3</sub><sup>•</sup>: The Role of the Amide Bond Revealed by Kinetic and Computational Studies
作者:Joses G. Nathanael、Uta Wille
DOI:10.1021/acs.joc.8b03224
日期:2019.3.15
free radical oxidant NO3• in its reactions with aliphatic amino acids and di- and tripeptides, suggesting that attack at the amide N–H bond in the peptide backbone is a highly viable pathway, which proceeds through a proton-coupled electron transfer (PCET) mechanism with a rate coefficient of about 1 × 106 M–1 s–1 in acetonitrile. Similar rate coefficients were determined for hydrogen abstraction from
动力学和计算数据表明,重要的环境自由基氧化剂NO 3 •在与脂肪族氨基酸以及二肽和三肽的反应中具有复杂的行为,这表明对肽主链中酰胺N–H键的攻击是高度可行的途径,这是通过质子耦合电子转移(PCET)机理进行的,在乙腈中的速率系数约为1×10 6 M –1 s –1。确定了类似的速率系数,用于确定侧链中α-碳和叔C–H键的夺氢作用。获得的NO 3 •反应速率系数带有脂族二肽和三肽的化合物表明,攻击在每个氨基酸残基的所有这些位点发生,这使得脂族肽序列极易受到NO 3 •诱导的氧化损伤的影响。NO 3 •与脂肪族肽中侧链的反应没有发现酰胺邻基效应的证据,酰胺邻基效应先前已发现可促进自由基诱导的苯丙氨酸侧链破坏。