Phosphopeptide anion characterization via sequential charge inversion and electron- transfer dissociation
Phosphopeptide anion characterization via sequential charge inversion and electron- transfer dissociation
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DOI：
10.1021/ac060164j
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发表时间：
2006-06-01
影响因子：
7.4
通讯作者：
McLuckey, Scott A.
中科院分区：
文献类型：
--
作者：
Gunawardena, Harsha P.;Emory, Joshua F.;McLuckey, Scott A.
连续的离子/离子反应已被用来表征存在于相对简单的多肽混合物中的磷肽，包括通过胰酶消化α-酪蛋白产生的磷肽。这些混合物中的磷酸肽通过正离子电喷雾电离产生低信号或无信号。然而，在负离子模式下产生了强烈的信号。最初的离子/离子反应使用多个质子化的端氨基树枝状大分子，将磷肽阴离子转化为双质子化物种。然后，双电荷阳离子进行离子/离子电子转移以诱导解离。双正电磷酸肽的电子转移解离可使N-C-α键沿肽骨架解离，同时保留不稳定的翻译后修饰，从而产生特有的c-和z型碎片离子。这些结果说明了在离子形成之后和结构询问之前改变离子电荷的能力。磷肽提供了一个例子，当它们存在于混合物中时，可能很难直接形成强烈的双电荷阳离子信号，因此，排除了使用电子转移解离作为结构探针的可能性。因此，这里描述的连续离子/离子反应过程可以为磷蛋白质组学中的结构询问提供新的能力。
Sequential ion/ion reactions have been used to characterize phosphopeptides present in relatively simple peptide mixtures, including one generated from the tryptic digestion of alpha-casein. The phosphopeptides in these mixtures gave rise to either low or no signals via positive ion electrospray ionization. Strong signals, however, were generated in the negative ion mode. An initial ion/ion reaction that employed multiply protonated amino-terminated dendrimers converted phosphopeptide anions to the doubly protonated species. The doubly charged cations were then subjected to ion/ion electron transfer to induce dissociation. Electron-transfer dissociation of doubly positively charged phosphopeptides yields characteristic c- and z-type fragment ions by dissociation of the N-C-alpha bond along the peptide backbone while preserving the labile posttranslational modifications. These results illustrate the ability to alter ion charge after ion formation and prior to structural interrogation. Phosphopeptides provide an example where it can be difficult to form strong doubly charged cation signals directly when they are present in mixtures, which, as a result, precludes the use of electron-transfer dissociation as a structural probe. The sequential ion/ion reaction process described here, therefore, can provide a new capability for structural interrogation in phosphoproteomics.