Initially, samples are proteolysed, the glycopeptides enriched by cation exchange
(CEX) and gel filtration (GF) and the glycans released enzymatically, whereby
PNGase A (and not PNGase F) is capable of releasing the core
α1,3-fucosylated N-glycans. Subsequent sub-fractionation by non-porous
graphitised carbon (NPGC) and/or reversed-phase (C18) resins result in pools
differing in terms of anionic and zwitterionic modifications. Finally, all
N-glycans are analysed by different types of HPLC (reversed or normal phase or
hydrophilic interaction/anion exchange; RP, NP or HIAX) in combination with
MALDI-TOF MS/MS and chemical/enzymatic treatments. The remaining O-glycopeptides
can be subject to β-elimination and LC-MS. The example structures, shown
according to the nomenclature of the Consortium for Functional Glycomics, are
from a marine snail.(12)