Zsiska M, Meyer B
Complex Carbohydrate Research Center, University of Georgia, Athens 30602.
Carbohydr Res. 1993 May 7;243(2):225-58. doi: 10.1016/0008-6215(93)87031-m.
1H NMR and 13C NMR spectral parameters of eight sulfated uronic acid containing disaccharides 1-8 were used to determine the conformational preferences that depend on the pattern of sulfation. Three sulfated derivatives of benzyl beta-D-Gal-(1-->4)-beta-D-GlcA (1), its 6'-sulfate 2, 4'-sulfate 3, and 4',6'-disulfate 4 were used as models for the beta-(1-->4) glycosidic linkage of chondroitin sulfates and three sulfated derivatives of benzyl beta-D-GlcA-(1-->3)-beta-D-Gal (5), its 6-sulfate 6, 4-sulfate 7, and 4,6-disulfate 8 were used as models for the beta-(1-->3) glycosidic linkage of chondroitin sulfates. To determine the dependence of conformational preferences on the charged groups, the sulfated disaccharides 2, 3, and 4 were compared to their unsulfated parent compound 1, and 6, 7, and 8 were compared to their parent compound 5. The 3JH-5,H-6 coupling constants were determined by high-order analysis of the spin systems, and from these the preferred populations of the hydroxymethyl groups were calculated. Selective 1D NOEs and ROEs were measured from H-1' across the glycosidic linkage to obtain the average distance of the protons adjacent to the glycosidic linkage. Derivatives of beta-D-Gal-(1-->4)-beta-D-GlcA carrying a sulfate group in the 6'-position (2) and in the 4'- and 6'-position (4) show a slight repulsive effect between the 6'-sulfate groups and the carboxylate group as expressed in small changes of the preferred populations of the glycosidic linkage and the sulfonyloxymethyl group. The 4-sulfate groups in 3 and 4 do not show a significant influence on the glycosidic linkage. However, the two sulfate groups in 4 exhibit a repulsive effect leading to a very high population of the gt conformation of the sulfonyloxymethyl group. In contrast hereto, the sulfate group at C-4 of beta-D-GlcA-(1-->3)-beta-D-Gal disaccharides 7 and 8 and the carboxylate group exert an attractive interaction that leads to a change of the conformation of the glycosidic linkage in 7 and 8 by about 30 degrees. The 6-sulfate groups of the disaccharides 6 and 8 show a slight repulsive interaction with the carboxylate and/or 4-sulfate group. Changes in 13C NMR chemical shifts support the interpretation obtained from the NOE and ROE analysis.(ABSTRACT TRUNCATED AT 400 WORDS)
八种含硫酸化糖醛酸的二糖1 - 8的1H NMR和13C NMR光谱参数用于确定取决于硫酸化模式的构象偏好。苄基β - D - Gal-(1→4)-β - D - GlcA（1）的三种硫酸化衍生物，其6'-硫酸酯2、4'-硫酸酯3和4',6'-二硫酸酯4用作硫酸软骨素β-(1→4)糖苷键的模型；苄基β - D - GlcA-(1→3)-β - D - Gal（5）的三种硫酸化衍生物，其6 - 硫酸酯6、4 - 硫酸酯7和4,6 - 二硫酸酯8用作硫酸软骨素β-(1→3)糖苷键的模型。为了确定构象偏好对带电基团的依赖性，将硫酸化二糖2、3和4与其未硫酸化的母体化合物1进行比较，将6、7和8与其母体化合物5进行比较。通过自旋系统的高阶分析确定3JH - 5,H - 6耦合常数，并由此计算羟甲基基团的优选构象比例。从H - 1'跨糖苷键测量选择性1D NOE和ROE，以获得与糖苷键相邻质子的平均距离。在6'-位（2）和4'-及6'-位（4）带有硫酸基团的β - D - Gal-(1→4)-β - D - GlcA衍生物显示出6'-硫酸基团与羧基之间存在轻微的排斥作用，这表现为糖苷键和磺酰氧基甲基基团优选构象比例的微小变化。3和4中的4 - 硫酸基团对糖苷键没有显著影响。然而，4中的两个硫酸基团表现出排斥作用，导致磺酰氧基甲基基团的gt构象比例非常高。与此相反，β - D - GlcA-(1→3)-β - D - Gal二糖7和8的C - 4位硫酸基团与羧基之间存在吸引相互作用，导致7和8中糖苷键的构象改变约30度。二糖6和8的6 - 硫酸基团与羧基和/或4 - 硫酸基团表现出轻微的排斥相互作用。13C NMR化学位移的变化支持了从NOE和ROE分析中获得的解释。（摘要截断于400字）
