Digested glycopeptides, selective

A shotgun glycoproteomics approach similar to that discussed in Section 9.12.2.4.2 has also been described,119 various steps of which are cleavage of glycoproteins, enrichment of glycopeptides in the digest by selective capture onto a modified solid support, release of peptides by PNGase treatment, and MS/MS analysis of the released peptide. Finally, the database search identifies the proteins. 

Geng, M., Zhang, X., Bina, M., Regnier, F. (2001). Proteomics of glycoproteins based on affinity selection of glycopeptides from tryptic digests. J. Chromatogr. B 752, 293-306. 

M. J. Huddleston, M. F. Bean, and S. A. Carr, Collisional fragmentation of glycopeptides by electrospray ionization LC/MS and LC/MS/MS Methods for selective detection of glycopeptides in protein digests, Anal. Chem., 65 (1993) 877-884. 

Ding, W., Hill, J.J., and Kelly, J. Selective enrichment of glycopeptides from glycoprotein digests using ion-pairing normal-phase liquid chromatography. Anal. Chem. 2007, 79, 8891-8899. 

A.P. Hunter, D.E. Games, Evaluation of glycosylation site heterogeneity and selective identification of glycopeptides in proteolytic digest of bovine CCj-acid glycoprotein by MS, Rapid Commun. Mass Spectrom., 9 (1995) 42. 

For selective detection of glycopeptides in the protein digest, an in-source CID strategy, similar to that used for phosphopeptides, is also applicable glycopeptides are analyzed using the positive-ion LC-ESI-SIM of the carbohydrate-specific marker ions.115 The oxonium ions of m/z 163 (Hex), 204 (HexNAc), 274 and 292 (NeuAc), and 366 (Hex-HexNAc) have served as marker ions. The precursor-ion scan of those ions (e.g., m/z 204) on a tandem mass spectrometer is another option to selectively identify glycopeptides. 

The complete structures of the carbohydrate units of three other glycopeptides from ovalbumin (62—64) have been established, using a combination of sequential digestion with glycosidases. Smith degradation, selective acetolysis, and methylation analysis. ... 

Huddleston, M.J. Bean, M.F. Carr, S.A. CoUisional Fragmentation of Glycopep-tides by Electrospray Ionization LC/MS and LC/MS/MS Methods for Selective Detection of Glycopeptides in Protein Digests. Anal. Chem. 1993,65, 877-884. 

On the other hand, on-target desalting within 3-AQ/CHCA droplet and selective detection of glycopeptides ions was reported (Sekiya, S. et al., 2008). Sekiya et al. found that 3-AQ/CHCA has a property to concentrate hydrophilic compounds on a small surface area of a matrix droplet (Sekiya, S. et al., 2008). Then it was confirmed by analyzing glycoprotein digests that glycopeptides were ionized from the center hydrophilic small area on 3-AQ/CHCA droplet whereas peptides were detected from the outer area on it (Fig. 10) (Sekiya, S. et al., 2008). 

The applications of electrospray (ion spray)-m.s. continue to broaden and have, this year, found utility for the identification of glycoprotein and glycopeptide firagments produced by enzymatic digestion.26 Regioisomeric esters of sucrose (e.g. 6-O-octanoyl and 6 -< -octanoyl) have been characterized by electrospray tandem m.s. Electrospray mass q>ectra for selected modified deoxynucleosides and deoxynucleoside monophosphates have been determined, and methods for intensity enhancement of MH described MH may be detected with as little as 3 pmol of substrate. ... 

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