Characterization of Tyrosine Nitration and Cysteine Nitrosylation Modifications by Metastable Atom-Activation Dissociation Mass Spectrometry
作者:Shannon L. Cook、Glen P. Jackson
DOI:10.1007/s13361-010-0041-4
日期:2011.2.1
The fragmentation behavior of nitrated and S-nitrosylated peptides were studied using collision induced dissociation (CID) and metastable atom-activated dissociation mass spectrometry (MAD-MS). Various charge states, such as 1+, 2+, 3+, 2–, of modified and unmodified peptides were exposed to a beam of high kinetic energy helium (He) metastable atoms resulting in extensive backbone fragmentation with significant retention of the post-translation modifications (PTMs). Whereas the high electron affinity of the nitrotyrosine moiety quenches radical chemistry and fragmentation in electron capture dissociation (ECD) and electron transfer dissociation (ETD), MAD does produce numerous backbone cleavages in the vicinity of the modification. Fragment ions of nitrosylated cysteine modifications typically exhibit more abundant neutral losses than nitrated tyrosine modifications because of the extremely labile nature of the nitrosylated cysteine residues. However, compared with CID, MAD produced between 66% and 86% more fragment ions, which preserved the labile –NO modification. MAD was also able to differentiate I/L residues in the modified peptides. MAD is able to induce radical ion chemistry even in the presence of strong radical traps and therefore offers unique advantages to ECD, ETD, and CID for determination of PTMs such as nitrated and S-nitrosylated peptides.
利用碰撞诱导解离(CID)和陨落原子激活解离质谱(MAD-MS)研究了硝化肽和S-亚硝基化肽的碎裂行为。将修饰肽和未修饰肽的各种电荷状态(如 1+、2+、3+、2-)暴露在高动能氦(He)惰性原子束中,会导致广泛的骨架破碎,并显著保留翻译后修饰(PTMs)。虽然硝基酪氨酸分子的高电子亲和力可以淬灭电子捕获解离(ECD)和电子转移解离(ETD)中的自由基化学反应和碎片,但 MAD 确实会在修饰附近产生大量的骨架裂解。亚硝基化半胱氨酸修饰的碎片离子通常比亚硝基化酪氨酸修饰的中性损失更多,这是因为亚硝基化半胱氨酸残基的性质极其易变。然而,与 CID 相比,MAD 产生的片段离子增加了 66% 至 86%,保留了易变的 -NO 修饰。MAD 还能区分修饰肽中的 I/L 残基。MAD 即使在强自由基捕获器存在的情况下也能诱导自由基离子化学反应,因此与 ECD、ETD 和 CID 相比,它在测定硝化肽和 S-亚硝基化肽等 PTMs 方面具有独特的优势。