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首页> 外文期刊>Journal of mass spectrometry: JMS >Reactivity of Tyr-Leu and Leu-Tyr dipeptides: identification of oxidation products by liquid chromatography-tandem mass spectrometry
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Reactivity of Tyr-Leu and Leu-Tyr dipeptides: identification of oxidation products by liquid chromatography-tandem mass spectrometry

机译：Tyr-Leu和Leu-Tyr二肽的反应性：液相色谱-串联质谱法鉴定氧化产物

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摘要

The exposure of peptides and proteins to reactive hydroxyl radicals results in covalent modifications of amino acid side-chains and protein backbone. In this study we have investigated the oxidation the isomeric peptides tyrosine-leucine (YL) and leucine-tyrosine (LY), by the hydroxyl radical formed under Fenton reaction (Fe2+/H2O2). Through mass spectrometry (MS), high-performance liquid chromatography (HPLC-MS) and electrospray tandem mass spectrometry (HPLC-MSn) measurements, we have identified and characterized the oxidation products of these two dipeptides. This approach allowed observing and identifying a wide variety of oxidation products, including isomeric forms of the oxidized dipeptides. We detected oxidation products with 1, 2, 3 and 4 oxygen atoms for both peptides; however, oxidation products with 5 oxygen atoms were only present in LY. LY dipeptide oxidation leads to more isomers with 1 and 2 oxygen atoms than YL (3 vs 5 and 4 vs 5, respectively). Formation of the peroxy group occurred preferentially in the C-terminal residue. We have also detected oxidation products with double bonds or keto groups, dimers (YL-YL and LY-LY) and other products as a result of cross-linking. Both amino acids in the dipeptides were oxidized although the peptides showed different oxidation products. Also, amino acid residues have shown different oxidation product depending on the relative position on the dipeptide. Results suggest that amino acids in the C-terminal position are more prone to oxidation.
机译：肽和蛋白质暴露于反应性羟基会导致氨基酸侧链和蛋白质骨架的共价修饰。在这项研究中，我们研究了在Fenton反应（Fe2 + / H2O2）下形成的羟基自由基氧化酪氨酸-亮氨酸（YL）和酪氨酸-酪氨酸的异构体。通过质谱（MS），高效液相色谱（HPLC-MS）和电喷雾串联质谱（HPLC-MSn）测量，我们已经鉴定并表征了这两个二肽的氧化产物。该方法允许观察和鉴定多种氧化产物，包括氧化二肽的异构形式。我们检测到两种肽均具有1、2、3和4个氧原子的氧化产物。但是，只有5个氧原子的氧化产物存在于LY中。 LY二肽氧化比YL导致更多的具有1和2个氧原子的异构体（分别为3对5和4对5）。过氧基团的形成优先发生在C末端残基中。由于交联，我们还检测到具有双键或酮基的氧化产物，二聚体（YL-YL和LY-LY）以及其他产物。尽管肽显示出不同的氧化产物，但是二肽中的两个氨基酸均被氧化。而且，根据二肽上的相对位置，氨基酸残基显示出不同的氧化产物。结果表明，C末端位置的氨基酸更易于氧化。

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