Application of high-performance liquid chromatography-electrospray ionization mass spectrometry and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry in combination with selective enzymatic modifications in the characterization of glycosylation patterns in single-chain plasminogen activator

• Published in: Journal of Chromatography A Vol. 732; no. 1; pp. 27 - 42
• Main Authors: Apffel, Alex, Chakel, John A., Hancock, William S., Souders, Carrie, M'Timkulu, Thabiso, Pungor, Erno
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 26.04.1996
• Subjects: Enzymes; Glycoproteins; Glycosylation; Pharmaceutical analysis; Enzymes; Glycosylation; Glycoproteins; Pharmaceutical analysis
• ISSN: 0021-9673
• DOI: 10.1016/0021-9673(95)01231-1

The application of high-performance liquid chromatography (HPLC), electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser-desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and selective enzymatic deglycosylation treatments is demonstrated in the analysis of glycosylation patterns in recombinant Desmodus salivary plasminogen activator, a heterogeneous glycoprotein. The sample was initially digested with a proteolytic enzyme (endoproteinase Lys-C) and then further treated with either PNGase F to remove N-linked carbohydrates or a combination of neuraminidase and O-glycosidase to remove sialic acid and O-linked carbohydrates. By comparison of the LC-ESI-MS peptide maps for the fully glycosylated and deglycosylated samples, it was possible to unambiguously identify the sites of N-linked glycosylation as well a number of N-linked glycopeptides. The O-linked glycopeptides, which are present at a low level (<1%), were not detected prior to the deglycosylation, nor could changes in peptide elution in the map following deglycosylation be correlated with potential O-linked glycosylation sites.