Complementary structural information of positive- and negative-ion MSn spectra of glycopeptides with neutral and sialylated N-glycans
Complementary structural information of positive- and negative-ion MSn spectra of glycopeptides with neutral and sialylated N-glycans
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DOI：
10.1002/rcm.2368
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发表时间：
2006-01-01
影响因子：
2
通讯作者：
Nishimura, SI
中科院分区：
文献类型：
--
作者：
Deguchi, K;Ito, H;Nishimura, SI
采用电喷雾电离线性离子阱飞行时间质谱法（esi - litt - tofms）和以氦为碰撞气体的碰撞诱导解离法（CID）获得了结合中性和唾液化n-聚糖的鸡蛋黄糖肽的正离子和负离子MSn谱。在正离子和负离子CID MSn （n = 2,3）光谱中观察到一些特征差异。在正离子MS2光谱中，肽段可能是稳定的，但中性n -聚糖部分引起了几个b型断裂，唾液化的n -聚糖几乎失去了唾液酸。相比之下，在负离子MS2光谱中，除了主链断裂外，肽段还引起了多个侧链和n -聚糖残基（如n -乙酰氨基葡萄糖（GlcNAc）残基）的断裂，但n -聚糖部分相对稳定。含有GlcNAc残基（203.1 Da）的质子化肽离子的正离子MS3光谱提供了足够的信息来确定包括糖基化位点在内的肽氨酸序列，而含有x -0,2(1)型交叉环切割（83.1 Da）的去质子化肽离子的负离子MS3光谱由于侧链和x -0,2(1)残基相关的片段而使肽序列分析复杂化。然而，对于糖肽的n -聚糖部分的结构信息，由去质子化（2,4）A(6)型交叉环切割离子（中性n -聚糖）或双去质子化b -6型片段离子（唾液化n -聚糖）得到的负离子CID MS3光谱比相应的正离子CID MS3光谱更能提供信息。因此，CID的正离子模式对包括糖基化位点在内的肽氨基酸序列的分析是有用的。CID的负离子模式对唾液化n -聚糖的结构分析特别有用。因此，在n -糖肽的结构分析中，它们的作用是互补的。版权所有(c) 2006约翰威利父子有限公司
Positive- and negative-ion MSn spectra of chicken egg yolk glycopeptides binding a neutral and a sialylated N-glycan were acquired by using electrospray ionization linear ion trap time-of-flight mass spectrometry (ESI-LIT-TOFMS) and collision-induced dissociation (CID) with helium as collision gas. Several characteristic differences were observed between the positive- and negative-ion CID MSn (n = 2,3) spectra. In the positive-ion MS2 Spectra, the peptide moiety was presumably stable, but the neutral N-glycan moiety caused several B-type fragmentations and the sialylated N-glycan almost lost sialic acid(s). In contrast, in the negative-ion MS2 spectra, the peptide moiety caused several side-chain and N-glycan residue (e.g., N-acetylglucosamine (GlcNAc) residue) fragmentations in addition to backbone cleavages, but the N-glycan moieties were relatively stable. The positive-ion MS3 spectra derived from the protonated peptide ion containing a GlcNAc residue (203.1 Da) provided enough information to determine the peptide amino-acid sequence including the glycosylation site, while the negative-ion MS3 spectra derived from the deprotonated peptide containing a X-0,2(1)-type cross-ring cleavage (83.1 Da) complicated the peptide sequence analysis due to side-chain and X-0,2(1) residue related fragmentations. However, for the structural information of the N-glycan moiety of the glycopeptides, the negative-ion CID MS3 spectra derived from the deprotonated (2,4)A(6)-type cross-ring cleavage ion (neutral N-glycan) or the doubly deprotonated B-6-type fragment ion (sialylated N-glycan) are more informative than are those of the corresponding positive-ion CID MS3 spectra. Thus, the positive-ion mode of CID is useful for the analyses of peptide amino-acid sequences including the glycosylation site. The negative-ion mode of CID is especially useful for sialylated N-glycan structural analysis. Therefore, in the structural analysis of N-glycopeptides, their roles are complementary. Copyright (c) 2006 John Wiley & Sons, Ltd.