Prof Yehia Mechref
Thursday, January 30, 2020 - 3:15pm to 4:15pm
Glycosylation is a common posttranslational modification that plays essential roles in biological systems, including cell signaling, adhesion, and communication. Recently, aberrant glycosylation has been proved to be associated with many diseases including cancers, which has prompted quantitative studies of glycomics and glycoproteomics. Thus, reliable approaches for glycan/glycoprotein identification and quantitation are necessary. Several MS-based glycomics and glycoproteomics methods that facilitate qualitative and quantitative characterization of glycans and glycopeptides will be discussed. The double-labeling method in which both glycans and proteins in cell culture for the direct quantitation of glycans, proteins, and glycopeptides will be described and discussed. This cell labeling also enables 32-multiplexing of glycomics with the addition of 8 isotopic iodomethane reagents and 18O-water. Additionally, we will present and discuss the isomeric separation of permethylated N- and O-glycans and glycopeptides recently achieved on PGC and C18 columns at high temperatures. Glycan and glycopeptide isomers are confirmed by retention time, MS2 pattern, exoglycosidase digestion, and structural modeling. Moreover, the isomeric separation of glycopeptides on PGC is achieved. Examples of biomedical studies highlighting the high sensitivity of the developed methods will be illustrated. Our innovative methods for reliable labeling and isomeric separation provide new insight into the biological attributes of glycoproteins in the development and progression of diseases.
Host: Prof Ronghu Wu