The Sequence-Specific Retention Calculator algorithm was adapted for the prediction of retention times of N-glycopeptides separated by reversed-phase high performance liquid chromatography (RPLC). Retention time shifts (dHI = HI glyco - HI deglyco, where HI is hydrophobicity index, measured in acetonitrile % units) used for modeling were measured for 602 glycopeptides vs. 123 of their deglycosylated analogs. Our method used a tryptic digestion of 12 purified glycoproteins, glycopeptide enrichment, deglycosylation with PNGaseF and RPLC-MS/MS analysis of combined (deglycosylated and intact) peptide mixtures. On average, glycosylation yields a 0.79% acetonitrile decrease in retention compared to their deglycosylated analogs. These values, however, are drastically different for asialo (-1.37), mono- (-0.47), di- (+0.61) and tri-sialylated (+1.94% acetonitrile) glycans.
Peptide retention time shifts upon glycosylation (dHI) vary depending on the
number of monosaccharide units, the presence/absence of sialic acid, peptide
hydrophobicity and a number of position-dependent features. The latter are
mostly driven by competing effects of acidic residues (aspartic acid, sialic
acid) on ion-pairing formation and nearest-neighbor effects of hydrophilic
glycans. The accuracy of the modified prediction model for glycopeptides
approaches that of prediction for non-modified species (R2 0.97 vs. 0.98).
However, retention time prediction based on experimental retention values of
deglycosylated analog (HI glyco = HI deglyco + dHI, R2=0.995) is much more
accurate, thus providing a solid support for glycopeptide identification in
complex samples based on mass and retention time.
[doi:10.25345/C5CM04]
[dataset license: CC0 1.0 Universal (CC0 1.0)]
Keywords: peptide retention time ; RP-HPLC ; glycosylation
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Principal Investigators: (in alphabetical order) |
Oleg Krokhin, University of Manitoba, Canada |
| Submitting User: | vspicer1 |
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