Why b, y's? Sodiation-induced tryptic peptide-like fragmentation of non-tryptic peptides
Why b, y's? Sodiation-induced tryptic peptide-like fragmentation of non-tryptic peptides
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DOI：
10.1016/j.ijms.2007.06.014
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发表时间：
2007-12-01
影响因子：
1.8
通讯作者：
Steen, Hanno
中科院分区：
文献类型：
--
作者：
Bensadek, Dalila;Monigatti, Flavio;Steen, Hanno
胰蛋白酶肽是蛋白质和肽的质谱分析的首选分析物，因为它们由于C-末端碱性氨基酸残基的存在而显示出有利的片段化模式。清洁的y碎片离子系列是最常见的观察到这些物种。相比之下，碱性氨基酸残基位置不确定的非胰蛋白酶肽产生B和y碎片离子的混合物，通常阻止碎片离子类型的明确分配，这反过来又阻碍了产物离子光谱的解释。在这里，我们报告的碎片化模式的多电荷离子胰蛋白酶肽可以通过片段化的monosodiated多电荷的物种，而不是多质子化的物种调制。即使当B碎片离子主导质子化物质的产物离子谱时，由于在N-末端存在电荷螯合碱性残基，在阳离子化物质断裂时观察到主要是单电荷钠阳离子化y碎片离子[y（n）+ Na]（+），即，实现了非胰蛋白酶肽的胰蛋白酶肽样片段化。这种片段化模式的几个例子进行了描述，从而强烈表明，钠阳离子可能是复杂的附近或在C-末端，甚至在其他酸性残基的肽内的存在下。这种效应在双电荷非胰蛋白酶肽的情况下尤其明显。非胰蛋白酶肽的片段化行为的这种受控调节显示出对于非胰蛋白酶生物活性肽的从头测序是有利的，因为它促进了B和y离子之间的区分。(C)2007 Elsevier B. V.保留所有权利。
Tryptic peptides are the analytes of choice for mass spectrometric analysis of protein and peptide as they display a favorable fragmentation pattern due to the presence of a C-terminal basic amino acid residue. Clean y fragment ion series is most commonly observed for these species. In contrast, non-tryptic peptides with undefined locations of basic amino acid residues give rise to a mixture of b and y fragment ions, often preventing unambiguous assignment of fragment ion types, which in turn impedes the interpretation of the product ion spectra. Here we report that the fragmentation pattern of multiply charged rion-tryptic peptides can be modulated by fragmenting the monosodiated multiply charged species instead of the multiply protonated species. Even when b fragment ions dominate the product ion spectrum of the protonated species clue to the presence of a charge sequestering basic residue at the N-terminus, mainly singly charged sodium cationized y fragment ions [y(n) + Na](+) are observed upon fragmentation of the cationized species, i.e., tryptic peptide-like fragmentation of non-tryptic peptides is achieved. Several examples of this fragmentation pattern are described, thus strongly suggesting that sodium cation may be complexed near or at the C-terminus even in the presence of other acidic residues within the peptide. This effect is especially pronounced in the case of the doubly charged non-tryptic peptides. This controlled modulation of the fragmentation behavior of non-tryptic peptides is shown to be advantageous for the de novo sequencing of non-tryptic bioactive peptides as it facilitates the differentiation between b and y ions. (C) 2007 Elsevier B.V. All rights reserved.