The chemical shifts of ring protons of the P-Man residue in a triantennary complex type N-linked glycan chain having a GlcNAcβ1→6(GlcNAcβ1→2)Manα1→6Manβ sequence were unambiguously determined by two-dimensional proton nuclear magnetic resonance (1H-NMR) spectroscopic methods. The chemical shift of H4 (3.84 ppm) of the β-Man residue was for the first time revealed to be different from those (~ 3.77 ppm) of biantennary and alternative type of triantennary glycans having a GlcNAcβ1→2Manα1→ 6Manβ sequence, but quite close to that (3.86 ppm) of a pentaantennary glycan containing a GlcNAcβ1→6 residue on the Manα1→6Manβ sequence. Thus, the addition of GlcNAcβ1→6 residue on the Man-4' residue, whose formation is catalyzed by GlcNAc transferase V, is considered to cause a down-field shift of β-Man H4 in the complex-type N-glycan chains. One possible explanation of this phenomenon is that the conformation of Manaα1→6 arm is folded back toward the proximal core region, as is the case with the complex-type N-glycan chains with the bisecting GlcNAc residue.
- 2D H-NMR
- Conformation of N-Iinked glycan
- GlcNAc transferase V
- Triantennary N-linked glycan
ASJC Scopus subject areas