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首页> 外文期刊>European journal of mass spectrometry >Characterization of oligosaccharides of the lactosamine series derived from keratan sulfates by tandem mass spectrometry
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Characterization of oligosaccharides of the lactosamine series derived from keratan sulfates by tandem mass spectrometry

机译：串联质谱法表征硫酸角质素衍生的乳糖胺系列低聚糖

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Positive- and negative-ion fast-atom bombardment tandem mass spectrometry with collision-induced dissociation (FAB-CID-MS/MS) has been used in the characterization of di-and tetra-saccharides of the lactosamine series from keratan sulfates. FAB-CID-MS/MS of Galβ1-4GlcNAc (L1) exhibited strong fragment ions originating from ring cleavage at the reducing-terminal sugar moiety together with glycosidic bond-cleavage ions, whereas GlcNAcβ1-3Gal (K1) showed strong glycosidic bond-cleavage ions but no ring-cleavage ions. A series of ring-cleavage fragment ions was observed with members of the L-series which have free hydroxyl groups at the C1 and C3 positions. CID-MS/MS spectra of the [M + Na - SO_3]~+ ion (m/z 406) from L2 and the [M + Na - 2SO_3]~+ ion (m/z 406) from L4 were almost identical with the CID-MS/MS spectrum of the [M + Na]~+ ion (m/z 406) from L1, which indicated that the sugar skeletons of L2 and L4 are the same as that of L1. On the other hand, the CID-MS/MS spectrum of the [M + Na - SO_3]~+ ion (m/z 508) from L4 did not resemble that of the [M + Na]~+ ion (m/z 508) from L2. The former showed peaks that were additional to the peaks in the latter. Since these extra peaks were accounted for on the basis of the structure of L3 [Gal250L?(6S)-4GlcNAc, S = sulfate], the in-source loss of sulfate groups by ester exchange upon FAB ionization takes place in a dual manner; one reaction at the non-reducing-terminal sugar to give L2 and the other at the reducing-terminal sugar to give L3. The CID-MS/MS spectra were characteristic for the tetrasaccharides L1-L1, L2-L2 and L4-L4 while in-source fragmentation confirms the component disaccharides of each tetrasaccharide. The structure of a tetrasaccharide trisulfate was confirmed as L2-L4 and not L4-L2 by CID-MS/MS. Negative-ion FAB-CID-MS/MS spectra of the sulfated di-and tetra-saccharides showed a pattern similar to that of the positive-ion spectra. Subtraction of the CID-MS/MS spectrum of the [M - H]~- ion of L2 [Galβ1-4GlcNAc(6S)] from that of the [M - H - SO_3]~- ion of L4 [Gal(6S)βl-4GlcNAc(6S)] gave several specific ions whose origins were nicely explained on the basis of the structure of L3. The structure of a pentasaccharide consisting of N-acetylneuraminic acid and a tetrasaccharide trisulfate was confirmed, on the basis of FAB-CID-MS/MS, as NeuNAcα2-6L2-L4.
机译：具有碰撞诱导解离的正离子和负离子快速原子轰击串联质谱（FAB-CID-MS / MS）已用于表征硫酸角质素中乳糖胺系列的二糖和四糖。 Galβ1-4GlcNAc（L1）的FAB-CID-MS / MS表现出强大的碎片离子，其起源于还原端糖部分的环裂解，同时具有糖苷键裂解离子，而GlcNAcβ1-3Gal（K1）表现出强糖苷键裂解。离子，但无环裂解离子。观察到一系列具有L-系列成员的环裂解碎片离子，这些离子在C1和C3位置具有游离羟基。来自L2的[M + Na-SO_3]〜+离子（m / z 406）和来自L4的[M + Na-2SO_3]〜+离子（m / z 406）的CID-MS / MS谱图与L1的[M + Na]〜+离子（m / z 406）的CID-MS / MS光谱，表明L2和L4的糖骨架与L1相同。另一方面，来自L4的[M + Na-SO_3]〜+离子（m / z 508）的CID-MS / MS谱图与[M + Na]〜+离子（m / z 508）。前者显示的峰是后者中的峰的补充。由于这些多余的峰是基于L3的结构[Gal250L？（6S）-4GlcNAc，S =硫酸盐]构成的，因此，FAB电离时通过酯交换发生的硫酸盐基团在源内的损失是双重发生的。方式;一个反应在非还原末端的糖上得到L2，另一个反应在还原末端的糖上得到L3。 CID-MS / MS光谱是四糖L1-L1，L2-L2和L4-L4的特征，而源内裂解证实了每种四糖的组分二糖。通过CID-MS / MS证实四糖三硫酸盐的结构为L2-L4而不是L4-L2。硫酸化二糖和四糖的负离子FAB-CID-MS / MS谱图显示出与正离子谱图相似的模式。 L2 [Galβ1-4GlcNAc（6S）]的[M-H]〜-离子的CID-MS / MS光谱与L4 [Gal（6S）]的[M-H-SO_3]〜-离子的CID-MS / MS光谱相减。 β1-4GlcNAc（6S）]给出了几种特定的离子，这些离子的来源根据L3的结构得到了很好的解释。基于FAB-CID-MS / MS，确认了由N-乙酰神经氨酸和四硫酸三硫酸酯组成的五糖的结构为NeuNAcα2-6L2-L4。

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