Teleman A, Siika-aho M, Sorsa H, Buchert J, Perttula M, Hausalo T, Tenkanen M
Technical Research Centre of Finland, Finland.
Carbohydr Res. 1996 Oct 23;293(1):1-13. doi: 10.1016/0008-6215(96)00170-x.
The tetrasaccharide 2"-O-(4-O-methyl-beta-L-idopyranosyluronic acid)xylotriose was isolated from enzymatically hydrolysed, unbleached, birch kraft pulp by anion-exchange chromatography in two steps. The primary structure of the tetrasaccharide was determined by 1H and 13C NMR spectroscopy, using homonuclear and heteronuclear two-dimensional techniques. NOE data and 3JH,H coupling constants show that the 4-O-methyl-beta-L-idopyranosyluronic acid in the tetrasaccharide is predominantly in the 1C4 chair conformation. The pKa value (3.17) for 4-O-methyliduronic acid attached beta-(1-->2) to xylose was determined from the pH-dependent chemical shift of H-5. The amount of 4-O-methyliduronic acid (0.1-0.5 mol%) in surface xylan of unbleached birch and pine kraft pulps was determined by extensive xylanase treatment and further analysis by NMR spectroscopy and high-performance anion-exchange chromatography.
通过阴离子交换色谱法分两步从酶解未漂白桦硫酸盐浆中分离出四糖2″-O-(4-O-甲基-β-L-艾杜吡喃糖醛酸)木三糖。采用同核和异核二维技术，通过1H和13C NMR光谱确定了该四糖的一级结构。NOE数据和3JH,H耦合常数表明，四糖中的4-O-甲基-β-L-艾杜吡喃糖醛酸主要处于1C4椅式构象。根据H-5的pH依赖性化学位移确定了与木糖以β-(1→2)连接的4-O-甲基艾杜糖醛酸的pKa值(3.17)。通过广泛的木聚糖酶处理以及进一步的NMR光谱和高效阴离子交换色谱分析，测定了未漂白桦和松木硫酸盐浆表面木聚糖中4-O-甲基艾杜糖醛酸的含量(0.1-0.5 mol%)。
