Horne A, Gettins P
Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232-0146.
Carbohydr Res. 1992 Feb 17;225(1):43-57. doi: 10.1016/0008-6215(92)80038-3.
Six heparin-derived oligosaccharides, ranging in size from di- to octa-saccharide and forming two closely related series differing in structure by the substitution of an unsulfated D-glucuronate for a 2-sulfated L-iduronate residue, have been characterized by 2-dimensional 1H-n.m.r. spectroscopy. In addition to providing new data on hexa- and octa-saccharides, several important changes to previously published data have been found for the two tetrasaccharides. The D-glucuronic acid H-5 proton is assigned to a resonance in the same region as resonances for the H-3 and H-4 D-glucuronate protons, rather than downfield from these resonances as earlier reported. The presence of D-glucuronic acid in the heparin sequence of the series-1 fragments affects the positions of neighboring D-glucosamine resonances, in particular shifting the anomeric proton signal in the preceding D-glucosamine 0.1-0.2 p.p.m. downfield. Resonances from the reducing-end D-glucosamines differ from internal D-glucosamine resonances both in relative position and in the degree of chemical shift difference between the H-6 and H-6' protons. This work illustrates the usefulness of two-dimensional techniques in determining heparin structure and emphasizes the need for direct analysis, rather than assignment by comparison to model compounds.
六种肝素衍生的寡糖，大小从二糖到八糖不等，形成两个结构紧密相关的系列，它们的结构差异在于一个无硫酸化的D-葡萄糖醛酸取代了一个2-硫酸化的L-艾杜糖醛酸残基，通过二维¹H-核磁共振光谱对其进行了表征。除了提供关于六糖和八糖的新数据外，还发现了之前发表的两种四糖数据的几个重要变化。D-葡萄糖醛酸的H-5质子被指定在与H-3和H-4 D-葡萄糖醛酸质子共振相同的区域，而不是像早期报道的那样在这些共振的低场。系列1片段的肝素序列中D-葡萄糖醛酸的存在会影响相邻D-葡萄糖胺共振的位置，特别是使前一个D-葡萄糖胺的异头质子信号在低场移动0.1 - 0.2 ppm。还原端D-葡萄糖胺的共振在相对位置以及H-6和H-6'质子之间的化学位移差异程度上都与内部D-葡萄糖胺共振不同。这项工作说明了二维技术在确定肝素结构方面的有用性，并强调了直接分析的必要性，而不是通过与模型化合物比较来进行归属。
