Electrochemical Oxidation and Cleavage of Tyrosine- and Tryptophan-Containing Tripeptides
Electrochemical Oxidation and Cleavage of Tyrosine- and Tryptophan-Containing Tripeptides
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DOI：
10.1021/ac101086w
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发表时间：
2010-09-15
影响因子：
7.4
通讯作者：
Bischoff, Rainer
中科院分区：
文献类型：
--
作者：
Roeser, Julien;Permentier, Hjalmar P.;Bischoff, Rainer
肽和蛋白质的电化学氧化已显示导致酪氨酸（Tyr）和色氨酸（Trp）残基旁边的特异性裂解，这使得电化学与质谱（EC-MS）的耦合成为化学和酶促裂解的潜在工具替代。一组含酪氨酸和色氨酸的三肽已被研究，以调查电化学氧化和随后的化学反应，包括肽键断裂的机理方面，使这第一次详细研究含色氨酸的肽的电化学。相邻氨基酸的影响进行了研究，得出的结论是，氧化和裂解产物的比例是肽依赖性的，相邻的氨基酸可以影响初始氧化步骤后发生的次级化学反应。参数的影响，如电位和溶剂条件表明，氧化电位的控制是至关重要的，以避免二聚体形成的酪氨酸和增加的氧插入（羟基化）的色氨酸，发生在1000 mV以上（相对于Pd/H-2）。虽然在第一氧化步骤后反应性中间体的形成并不强烈依赖于实验条件，但良好的裂解产率需要酸性pH。在强酸性条件（pH 1.9-3.1）下工作导致最佳裂解产率（40-80%），而在碱性条件下没有或很少发生裂解。在线EC-MS允许确定最大裂解产率的最佳潜力，而EC-LC MS/MS揭示了反应产物的性质和分布。
Electrochemical oxidation of peptides and proteins has been shown to lead to specific cleavage next to tyrosine (Tyr) and tryptophan (Trp) residues which makes the coupling of electrochemistry to mass spectrometry (EC-MS) a potential instrumental alternative to chemical and enzymatic cleavage. A set of Tyr and Trp-containing tripeptides has been studied to investigate the mechanistic aspects of electrochemical oxidation and the subsequent chemical reactions including peptide bond cleavage, making this the first detailed study of the electrochemistry of Trp-containing peptides. The effect of adjacent amino acids was studied leading to the conclusion that the ratios of oxidation and cleavage products are peptide-dependent and that the adjacent amino acid can influence the secondary chemical reactions occurring after the initial oxidation step. The effect of parameters such as potential and solvent conditions showed that control of the oxidation potential is crucial to avoid dimer formation for Tyr and an increasing number of oxygen insertions (hydroxylations) for Trp, which occur above 1000 mV (vs Pd/H-2). While the formation of reactive intermediates after the first oxidation step is not strongly dependent on experimental conditions, an acidic pH is required for good cleavage yields. Working under strongly acidic conditions (pH 1.9-3.1) led to optimal cleavage yields (40-80%), whereas no or little cleavage occurred under basic conditions. Online EC-MS allowed determining the optimal potential for maximum cleavage yields, whereas EC-LC MS/MS revealed the nature and distribution of the reaction products.