LC/MSn for glycoprotein analysis: N-linked glycosylation analysis and peptide sequencing of glycopeptides.

Liquid chromatography/multiple-stage mass spectrometry (LC/MS( n )) is an effective means for the site-specific glycosylation analysis of a limited quantity of glycoproteins, such as gel-separated proteins. Generally, a tryptic digest of the glycoprotein is separated by reversed-phase LC, and peptide sequencing and glycosylation analysis are achieved with on-line MS( n ). In this chapter, a protocol for the LC/MS/MS/MS of a proteolytic digest of a gel-separated glycoprotein is described.