Poppe L, York W S, van Halbeek H
Complex Carbohydrate Research Center, University of Georgia, Athens 30602.
J Biomol NMR. 1993 Jan;3(1):81-9. doi: 10.1007/BF00242477.
A method for measuring three-bond 13C-1H scalar coupling constants across glycosidic bonds in a cyclic beta(1-->2)-glucan icosamer is presented. This oligosaccharide molecule, with its high degree of symmetry, represents a particular challenge for NMR spectroscopy to distinguish inter-residue from intra-residue heteronuclear coupling effects. Chemically equivalent H2 protons in adjacent glucosyl residues are distinguished on the basis of their different through-space, dipolar interactions with the anomeric protons (H1). The strong NOE contact between anomeric (H1) and aglyconic (H2') protons permits the selective observation of the inter-residue heteronuclear couplings 3JC1H2' and 3JC2'H1 in a natural-abundance 13C-omega 1-half-filtered (1H,1H)ROESY experiment.
本文提出了一种测量环状β(1→2)-葡聚糖二十聚体中糖苷键上三键13C-1H标量耦合常数的方法。这种具有高度对称性的寡糖分子，对核磁共振波谱法区分残基间与残基内的异核耦合效应而言是一项特殊挑战。相邻葡萄糖残基中化学等价的H2质子，基于它们与异头质子（H1）不同的空间偶极相互作用而得以区分。异头（H1）质子与苷元（H2'）质子之间强烈的核Overhauser效应（NOE）接触，使得在天然丰度的13C-ω1-半滤波(1H,1H)旋转核Overhauser效应光谱（ROESY）实验中能够选择性地观测到残基间异核耦合3JC1H2'和3JC2'H1。
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