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Glycan Identification & Characterization

Glycomics is the comprehensive study of glycan structures. Currently, glycans are attracting attention from the scientific community as potential biomarkers or as post-translational modifications (PTMs) of therapeutic proteins. For example, glycans on the surface of cells mediate interactions between cells and define cellular identities within complex tissues at all stages of animal life. In addition, specific glycan structures control the activities of the proteins to which they are attached, adding a post-transcriptional, post-translational layer of regulation onto protein function. Many glycans show disease-related expression level changes. In some instances, the function of specific cell-surface signaling molecules requires the elucidation of an exact glycan structure at a precise site on an appropriate protein.

The most common and widely studied forms of glycans are the N-linked and O-linked glycans. N-linked glycans are attached to the amide group of asparagines (Asn) residues in a consensus Asn-X-Ser/Thr sequence (X can be any amino acid except proline). O-linked glycans are linked to the hydroxyl group on serine (Ser) or threonine (Thr) residues. Other forms of glycans are known but less well studied. These include glycosylphosphatidylinositol anchors attached to the protein carboxyl terminus, C-glycosylation that occurs on tryptophan residues, and S-linked glycosylation through a sulfur atom on cysteine or methionine. Mass spectrometry (MS) has emerged as one of the most powerful tools for the structural elucidation of glycans. This is due to its sensitivity of detection and its ability to analyze complex mixtures of glycans derived from a variety of organisms and cell lines.

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Workflow Overview for Glycan Identification and Characterization

The attractive feature of mass spectrometry based methods, compared to other techniques for glycan analysis, is the maximization of structural information relative to the amount of time, labor and sample quantity.  In addition to the characterization of the glycan sequence, mass spectrometry can provide information about branching patterns and the location of possible substituents. To facilitate analysis, glycans are subjected to enzymatic or chemical release depending upon the type of glycan examined. The released glycans are then derivatized and introduced into the MS for analysis.

Additional Resources

Biopharma Glycomics Community

Guide To Glycan Analysis

Glycan Analysis for Biotherapeutics

The Sweet Revolution in Mass Spectrometry Based Characterization of Glycans