Dataset Information

Xylose Migration During Tandem Mass Spectrometry of N-Linked Glycans.

ABSTRACT: Understanding the rearrangement of gas-phase ions via tandem mass spectrometry is critical to improving manual and automated interpretation of complex datasets. N-glycan analysis may be carried out under collision induced (CID) or higher energy collision dissociation (HCD), which favors cleavage at the glycosidic bond. However, fucose migration has been observed in tandem MS, leading to the formation of new bonds over four saccharide units away. In the following work, we report the second instance of saccharide migration ever to occur for N-glycans. Using horseradish peroxidase as a standard, the beta-1,2 xylose was observed to migrate from a hexose to a glucosamine residue on the (Xyl)Man3GlcNac2 glycan. This investigation was followed up in a complex N-linked glycan mixture derived from stem differentiating xylem tissue, and the rearranged product ion was observed for 75% of the glycans. Rearrangement was not favored in isomeric glycans with a core or antennae fucose and unobserved in glycans predicted to have a permanent core-fucose modification. As the first empirical observation of this rearrangement, this work warrants dissemination so it may be searched in de novo sequencing glycan workflows. Graphical Abstract ?.

SUBMITTER: Hecht ES

PROVIDER: S-EPMC5373971 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature

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Xylose Migration During Tandem Mass Spectrometry of N-Linked Glycans.

Hecht Elizabeth S ES Loziuk Philip L PL Muddiman David C DC

Journal of the American Society for Mass Spectrometry 20170126 4

Understanding the rearrangement of gas-phase ions via tandem mass spectrometry is critical to improving manual and automated interpretation of complex datasets. N-glycan analysis may be carried out under collision induced (CID) or higher energy collision dissociation (HCD), which favors cleavage at the glycosidic bond. However, fucose migration has been observed in tandem MS, leading to the formation of new bonds over four saccharide units away. In the following work, we report the second instan ...[more]

PMID: 28127681

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Project description:Ion mobility-mass spectrometry (IM-MS) has become a powerful tool for glycan structural characterization due to its ability to separate isomers and provide collision cross section (CCS) values that facilitate structural assignment. However, IM-based isomer analysis may be complicated by the presence of multiple gas-phase conformations of a single structure that not only increases difficulty in isomer separation but can also introduce the possibility for misinterpretation of conformers as isomers. Here, the ion mobility behavior of several sets of isomeric glycans, analyzed as their permethylated derivatives, in both nonreduced and reduced forms, was investigated by gated-trapped ion mobility spectrometry (G-TIMS). Notably, reducing-end reduction, commonly performed to remove anomerism-induced chromatographic peak splitting, did not eliminate the conformational heterogeneity of permethylated glycans in the gas phase. At a mobility resolving power of ∼100, 14 out of 22 structures showed more than one conformation. These results highlight the need to use IMS devices with high mobility resolving power for better separation of isomers and to acquire additional structural information that can differentiate isomers from conformers. Online electronic excitation dissociation (EED) MS/MS analysis of isomeric glycan mixtures following G-TIMS separation showed that EED can generate isomer-specific fragments while producing nearly identical tandem mass spectra for conformers, thus allowing confident identification of isomers with minimal evidence of any ambiguity resulting from the presence of conformers. G-TIMS EED MS/MS analysis of N-linked glycans released from ovalbumin revealed that several mobility features previously thought to arise from isomeric structures were conformers of a single structure. Finally, analysis of ovalbumin N-glycans from different sources showed that the G-TIMS EED MS/MS approach can accurately determine the batch-to-batch variations in glycosylation profiles at the isomer level, with confident assignment of each isomeric structure.

Project description:PubChem serves as a comprehensive repository, housing over 100 million unique chemical structures representing the breadth of our chemical knowledge across numerous fields including metabolism, pharmaceuticals, toxicology, cosmetics, agriculture, and many more. Rapid identification of these small molecules increasingly relies on electrospray ionization (ESI) paired with tandem mass spectrometry (MS/MS), particularly by comparison to genuine standard MS/MS data sets. Despite its widespread application, achieving consistency in MS/MS data across various analytical platforms remains an unaddressed concern. This study evaluated MS/MS data derived from one hundred molecular standards utilizing instruments from five manufacturers, inclusive of quadrupole time-of-flight (QTOF) and quadrupole orbitrap "exactive" (QE) mass spectrometers by Agilent (QTOF), Bruker (QTOF), SCIEX (QTOF), Waters (QTOF), and Thermo QE. We assessed fragment ion variations at multiple collisional energies (0, 10, 20, and 40 eV) using the cosine scoring algorithm for comparisons and the number of fragments observed. A parallel visual analysis of the MS/MS spectra across instruments was conducted, consistent with a standard procedure that is used to circumvent the still prevalent issue of mischaracterizations as shown for dimethyl sphingosine and C20 sphingosine. Our analysis revealed a notable consistency in MS/MS data and identifications, with fragment ions' m/z values exhibiting the highest concordance between instrument platforms at 20 eV, the other collisional energies (0, 10, and 40 eV) were significantly lower. While moving toward a standardized ESI MS/MS protocol is required for dependable molecular characterization, our results also underscore the continued importance of corroborating MS/MS data against standards to ensure accurate identifications. Our findings suggest that ESI MS/MS manufacturers, akin to the established norms for gas chromatography mass spectrometry instruments, should standardize the collision energy at 20 eV across different instrument platforms.

Dataset Information

Xylose Migration During Tandem Mass Spectrometry of N-Linked Glycans.

Publications

Xylose Migration During Tandem Mass Spectrometry of N-Linked Glycans.

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