Enhancing glycopeptide characterisation by enrichment from glycoproteins using microcolumns containing the Zic-Hilic zwitterionic stationary phase
The characterisation of glycopeptides that originate from N-glycosylated proteins which are separated by gel electrophoresis typically requires a large amount of starting material because the compounds of interest are present at relatively low levels.
This may create a significant problem as the acquisition of larger samples may be exceedingly difficult and the sample preparation may be quite complex, leading to low yields of the glycoproteins.
A recent study, 'Enrichment and characterisation of glycopeptides from gel-separated glycoproteins', Thaysen-Andersen and Hojrub, American Biotechnology Laboratory, May 2006, reports that considerably smaller samples are required when the glycopeptides are separated from the sample (bovine fetuin) using a microcolumn containing Zic-Hilic hydrophilic interaction chromatographic media.
The in-gel proteolytic digested sample is dried and dissolved in 80% acetonitrile with 2% TFA and loaded onto the column.
After washing with buffer, the glycopeptides can be eluted with 2% formic acid and deposited onto a Maldi target for structure determination.
Alternatively, the glycopeptides were deglycosylated using PNGase F to obtain the complete set of deglycosylated peptides for mass spectral studies.
Zic-Hilic, is an extremely versatile stationary phase that is based on zwitterionic sulphobetaine groups that is gycoselective and excludes regular hydrophobic tryptic peptides.
The selectivity of the stationary phase and the elimination of the regular peptides (which dominated the mass spectrum) allowed for considerably greater sensitivity.
In addition to its use in a microcolumn to extract the various glycoproteins, Zic-Hilic is commonly used as the stationary phase for the HPLC separation of glycopeptides.
