High sensitivity identification of sulfated glycans carried on specific sites of glycoproteins is an important requisite for investigation of molecular recognition events involved in diverse biological processes. However, aiming for resolving site-specific glycosylation of sulfated glycopeptides by direct LC-MS² sequencing is technically most challenging. Other than the usual limiting factors such as lower abundance and ionization efficiency compared to analysis of non-glycosylated peptides, confident identification of sulfated glycopeptides among the more abundant non-sulfated glycopeptides requires additional considerations in the selective enrichment and detection strategies. Metal oxide has been applied to enrich phosphopeptides and sialylated glycopeptides, but its use to capture sulfated glycopeptides has not been investigated. Likewise, various complementary MS² fragmentation modes have yet to be tested against sialylated and non-sialylated sulfoglycopeptides due to limited appropriate sample availability. In this study, we have investigated the feasibility of sequencing tryptic sulfated N-glycopeptide and its MS² fragmentation characteristics by first optimizing the enrichment methods to allow efficient LC-MS detection and MS² analysis by a combination of CID, HCD, ETD, and EThcD on hybrid and tribrid Orbitrap instruments. Characteristic sulfated glyco-oxonium ions and direct loss of sulfite from precursors were detected as evidences of sulfate modification. It is anticipated that the technical advances demonstrated in this study would allow a feasible extension of our sulfoglycomic analysis to sulfoglycoproteomics.

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糖蛋白特定位点上携带的硫酸化聚糖的高灵敏度鉴定是研究涉及多种生物学过程的分子识别事件的重要条件。然而，旨在通过直接LC-MS ²解决硫酸化糖肽的位点特异性糖基化排序在技术上是最具挑战性的。除了通常的限制因素（如与非糖基化肽段的分析相比，较低的丰度和电离效率）外，要在更丰富的非硫酸化糖基肽中确定硫酸化糖基肽的可信度，还需要在选择性富集和检测策略中进行其他考虑。金属氧化物已被用于富集磷酸肽和唾液酸化糖肽，但尚未研究其用于捕获硫酸化糖肽的用途。同样，由于有限的适当样品可用性，尚未针对唾液酸化和非唾液酸化的磺基糖肽测试各种互补的MS ²断裂模式。在这项研究中，我们研究了测序胰蛋白酶性硫酸盐N的可行性。糖肽及其MS ²片段化特性，方法是首先优化富集方法，以通过在混合和三重Orbitrap仪器上结合CID，HCD，ETD和EThcD进行有效的LC-MS检测和MS ²分析。检测到特征性硫酸化的糖-氧鎓离子和亚硫酸盐从前体中的直接损失，作为硫酸盐修饰的证据。可以预料的是，这项研究中展示的技术进步将使我们的糖酵解分析切实可行地扩展到磺基糖体药物。

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