University of Bayreuth, Bioorganic Chemistry, Universitätsstraße 30, 95447, Bayreuth, Germany.
Dpto. Química Orgánica I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, Avd. Complutense s/n, 28040, Madrid, Spain.
Chembiochem. 2020 Nov 16;21(22):3212-3215. doi: 10.1002/cbic.202000268. Epub 2020 Aug 19.
In human serum immunoglobulin G (IgG), a rare modification of biantennary complex N-glycans lead to a β1,4-galactosylated bisecting GlcNAc branch. We found that the bisecting GlcNAc on a biantennary core-fucosylated N-glycan was enzymatically galactosylated under stringent reaction conditions. Further optimizations led to an efficient enzymatic approach to this particular modification for biantennary substrates. Notably, tri- and tetra-antennary complex N-glycans were not converted by bovine galactosyltransferase. An N-glycan with a galactosylated bisecting GlcNAc was linked to a lanthanide binding tag. The pseudo-contact shifts (PCS) obtained from the corresponding Dy-complex were used to calculate the conformational preferences of the rare N-glycan. Besides two extended conformations only a single folded conformation was found.
在人血清免疫球蛋白 G（IgG）中，双天线复合 N-聚糖的罕见修饰导致β1,4-半乳糖基化的双分叉 GlcNAc 分支。我们发现，在双天线核心岩藻糖基化的 N-聚糖上的双分叉 GlcNAc 在严格的反应条件下可被酶法半乳糖基化。进一步的优化导致了针对双天线底物的这种特殊修饰的有效酶法方法。值得注意的是，牛半乳糖基转移酶不会转化三天线和四天线复合 N-聚糖。具有半乳糖基化双分叉 GlcNAc 的 N-聚糖与镧系元素结合标签相连。从相应的 Dy 配合物获得的伪接触位移（PCS）用于计算罕见 N-聚糖的构象偏好。除了两种扩展构象外，仅发现了一种折叠构象。
