Zou W, Brisson J R, Yang Q L, van der Zwan M, Jennings H J
Institute for Biological Sciences, National Research Council of Canada, Ottawa, Canada.
Carbohydr Res. 1996 Dec 13;295:209-28. doi: 10.1016/s0008-6215(96)90144-5.
For the purpose of carrying out a comprehensive investigation into the nature of the conformational epitope of the type III group B Streptococcus polysaccharide, combined chemical and enzymatic methods were applied to the synthesis of three decasaccharide probes, namely beta-D-Glc-(1-->6)[alpha-NeuR-(2-->3)-beta-D-Gal-(1-->4)] -beta-D-GlcNAc-(1-->3)-beta-D-Gal-(1-->4)-beta-D- Glc-(1-->6)[alpha-NeuR-(2-->3)-beta-D-Gal-(1-->4)]-beta-D-GlcNAc-( 1-->3) -beta-D-Gal-OMe (22 NeuR = NeuAc; 23 NeuR = NeuAc with 8% 13C-labeling; 24 NeuR = NeuPr). The precursor core octasaccharide 21 was chemically synthesized from trisaccharide donor 11 and pentasaccharide acceptor 19 by block condensation. Sialylation of 21 with alpha-(2-->3)-sialyltransferase and CMP-NeuAc afforded 22. In the presence of CMP-sialic acid synthetase and alpha-(2-->3)-sialyltransferase, 21 was sialylated with sialic acid derivatives (8% 13C-labeled, or N-propionyl substituted) to give 23 and 24, respectively. Complete assignments of the 1H and 13C NMR spectra of compounds 21, 22 (23), and 24 are also presented.
为了全面研究B族链球菌III型多糖构象表位的性质，采用化学和酶促相结合的方法合成了三种十糖探针，即β-D-葡萄糖-(1→6)[α-神经氨酸-(2→3)-β-D-半乳糖-(1→4)]-β-D-乙酰葡糖胺-(1→3)-β-D-半乳糖-(1→4)-β-D-葡萄糖-(1→6)[α-神经氨酸-(2→3)-β-D-半乳糖-(1→4)]-β-D-乙酰葡糖胺-(1→3)-β-D-半乳糖-甲酯（22：神经氨酸=唾液酸；23：神经氨酸=8% 13C标记的唾液酸；24：神经氨酸=N-丙酰基取代的唾液酸）。前体核心八糖21由三糖供体11和五糖受体19通过片段缩合化学合成。用α-(2→3)-唾液酸转移酶和CMP-神经氨酸对21进行唾液酸化得到22。在CMP-唾液酸合成酶和α-(2→3)-唾液酸转移酶存在下，21分别用唾液酸衍生物（8% 13C标记的或N-丙酰基取代的）进行唾液酸化，得到23和24。还给出了化合物21、22（23）和24的1H和13C NMR谱的完全归属。
