Table 3.
Acceptor substrate specificity of human C2GnT1 and C2GnT2. C2GnT1 and C2GnT2 were assayed as described in Material and methods with 0.5 mM Galβ1–3GalNAcα-pnp as the standard acceptor substrate (set to 100% activity). Bn, benzyl; GalN, D-galactosamine; pnp, p-nitrophenyl; onp, o-nitrophenyl. Bold S and T in glycopeptides indicate the attachment of O-glycans.
| Compound name (0.5 mM in assays) | C2GnT1 activity (%) | C2GnT2 activity (%) |
|---|---|---|
| Galβ1–3GalNAcα-pnp (Core1-pnp) | 100a | 100b |
| Section I: modifications of the aglycone | ||
| Galβ1–3GalNAcα-Bn (Core1-Bn) | 64 | 35 |
| Galβ1–3GalNAcα-perillyl | 135 | 86 |
| Galβ1–3GalNAcα-onp | 79 | 100 |
| Section II: modifications of the sugar moiety | ||
| GalNAcα-Bn | <1 | <1 |
| 2-N-Butyryl-GalNα-Bn | <1 | <1 |
| GlcNAcβ1–3-Galβ-methyl | <1 | <1 |
| GlcNAcβ1–3GalNAcα-pnp (Core 3-pnp) | <1 | 32 |
| GlcNAcβ1–3GalNAcα-allyl | <1 | 27 |
| Galβ1–3GlcNAcα-Bn | <1 | <1 |
| Fucα1–2Galβ1–3GalNAcα-methyl | <1 | <1 |
| 3-Deoxy-GalNAcα-Bn | <1 | <1 |
| Galβ1–3(6-deoxy)GalNAcα-Bn | <1 | <1 |
| GlcNAcβ1–6GalNAcα-Bn (Core 6-Bn) | <1 | <1 |
| Galβ1–3(4-deoxy)GalNAcα-Bn | <1 | <1 |
| Galβ1–3(6-O-methyl)GalNAcα-Bn | <1 | <1 |
| 3-Deoxy-Galβ1–3GalNAcα-Bn | 90 | 52 |
| 3-O-Methyl-Galβ1–3GalNAcα-Bn | 104 | 41 |
| Galβ1–3GlcNAcβ1–3Galβ1–3GalNAcα-Bn | <1 | <1 |
| 4-Deoxy-Galβ1–3GalNAcα-Bn | <1 | <1 |
| 4-F-4-Deoxy-Galβ1–3GalNAcα-Bn | <1 | <1 |
| 6-Deoxy-Galβ1–3GalNAcαBn | <1 | <1 |
| GlcNAcβ1–6(GlcNAcβ1–3)GalNAcα-Bn (Core 4-Bn) | <1 | <1 |
| Section III: glycopeptides | ||
| (Galβ1–3GalNAcα)TAGV | 92 | <1 |
| T-(GlcNAcβ1–3GalNAcα)TTVTPTPTG | <1 | <1 |
| TETTSHS-(GlcNAcβ1–3GalNAcα)TPG | <1 | <1 |
| TET-(GlcNAcβ1–3GalNAcα)TSHSTPG | <1 | <1 |
| TE-(GlcNAcβ1–3GalNAcα)TTSHSTPG | <1 | <1 |
| TE-(GlcNAcβ1–6GalNAcα)TTSHSTPG | <1 | <1 |
| TT-(Galβ1–3GalNAcα)TVTPTPTG | 13 | <1 |
| T-(Galβ1–3GalNAcα)TTVTPTPTG | 11 | <1 |
| TT-(Galβ1–3GalNAcα)TVTP-(Galβ1–3GalNAcα)TPTG | 12 | <1 |
| TETTSHS-(Galβ1–3GalNAcα)TPG | 70 | 7 |
| TET-(Galβ1–3GalNAcα)TSHSTPG | 27 | <1 |
| Ac-PTT-(Galβ1–3GalNAcα)TGIST-NH2 | 36 | <1 |
| Ac-PT-(Galβ1–3GalNAcα)TTGIST-NH2 | 49 | 6 |
| Ac-P-(Galβ1–3GalNAcα)TTTGIST-NH2 | 7 | <1 |
| Ac-GTT-(Galβ1–3GalNAcα)TPIST-NH2 | 14 | <1 |
| Ac-GT-(Galβ1–3GalNAcα)TTPIST-NH2 | 13 | 5 |
| Ac-G-(Galβ1–3GalNAcα)TTTPIST-NH2 | 12 | 8 |
| Ac-PT-(Galβ1–3GalNAcβ)TTPIST-NH2 | 43 | 15 |
| Ac-P-(Galβ1–3GalNAcβ)TTTPIST-NH2 | 72 | 32 |
| AHGVT-(GalNAcα)SAPDTRPAPGSTAPPA | <1 | <1 |
| AHGVT-(Galβ1–3GalNAcα)SAPDTRPAPGSTAPNA | 9 | <1 |
| AHGVT-(Galβ1–3GalNAcα)SAPESRPAPGSTAPNA | 9 | <1 |
| AHGVT-(Galβ1–3GalNAcα)SAPDTRPAPGSTAPTA | 9 | <1 |
| AHGVT-(Galβ1–3GalNAcα)SAPETRPAPGSTAPTA | 11 | <1 |
| AHGVT-(Galβ1–3GalNAcα)SAPDTRPAPGSTAP- (Galβ1–3GalNAcα)TA | 18 | <1 |
| AHGVT-(Galβ1–3GalNAcα)SAPDTRPAPGS- (Galβ1–3GalNAcα)SAPPA | 9 | <1 |
a
100% C2GnT1 activity corresponds to 0.034 μmol/h/mg.
b
100% C2GnT2 activity corresponds to 0.220 μmol/h/mg.