Glycoproteomics using chemical immobilization.

Protein glycosylation is prevalent in proteins destined for extracellular environments, e.g., transmembrane proteins, cell surface proteins, and secreted proteins in tissues and body fluids. These also are the proteins that are most easily accessible for diagnostic and therapeutic purposes. This unit describes methods for solid-phase extraction of glycopeptides and subsequent identification of glycopeptides as well as glycosylation sites. The extraction is based on the conjugation of glycopeptides to a solid support, using hydrazide chemistry, and the specific release of formerly glycosylated peptides. The recovered peptides are then identified by tandem mass spectrometry. The methods are applied to the analysis of proteins from cells, body fluids, and tissues.