Table II. Glycosylation sites, (glyco)peptide sequences, non-glycosylated glycopeptide masses (Da), N-glycan occupancies, degrees of fucosylation, degrees of sialylation and distribution of branching as well as the relative accessibility to the individual glycosylation sites. These results are based on glycopeptide profiling.
| Glycosylation site (residue) | Glycopeptide (trypsin + Asp-N generated) | Non-glycosylated glycopeptide mass | N-Glycan occupancy | Degree of fucosylation | Degree of sialylation (mol NeuAc/mol N-Glycan) | Branching distribution (B:T:Te:P)b | Relative accessibility to sitec |
|---|---|---|---|---|---|---|---|
| 1 (Asn9) | Met1-Arg15 | 1755.76 Da | 96.7% | 17.2% | 100% (2.45) | 48:50:2:0 | N/A |
| 2 (Asn74) | Ala65-Arg78 | 1558.85 Da | 99.5% | 13.7% | 100% (2.86) | 21:35:41:3 | 1.00 |
| 3 (Asn154) | Asn154-Lys155 | 260.15 Da | 89.0%a | 14.1%a | 100% (2.18)a | 76:21:2:0a | 0.80 |
| 4 (Asn238) | Asp223-Pro246 | 2740.32 Da | 70.5% | 0.0% | 100% (2.10) | 79:21:0:0 | 0.28 |
| 5 (Asn308) | Asp301-Arg311 | 1311.62 Da | 96.3% | 4.7% | 100% (2.26) | 71:29:0:0 | 0.23 |
| 6 (Asn347) | Asp337-Arg356 | 2056.15 Da | 84.7% | 34.9% | 100% (2.89) | 18:71:9:2 | N/A |
| Global (CBG) | 5.4 mol glycan/mol CBG | 0.76 mol Fuc/mol CBG | 13.3 mol NeuAc/mol CBG | 51:38:10:1 |
a The quantitation and occupancy of N-glycans from this glycosylation site were determined from a separate digest exclusively with endoproteinase Asp-N generating the (glyco)peptide Asp140-Val161 (2506.33 Da).
b It was not possible to determine whether N-glycans with five LacNAc units attached to the core were a mix of penta-antennary and tetra-antennary structures with one LacNAc extension.
c See ‘Experimental Procedures’ and supplementary Fig. S4 for information on the relative accessibility to the individual glycosylation sites.