Jarrell H, Singh D, Grant C W
Department of Biochemistry, University of Western Ontario, London, Canada.
Biochim Biophys Acta. 1992 Jan 31;1103(2):331-4. doi: 10.1016/0005-2736(92)90105-u.
Galactosylceramide (GalCer) and the ganglioside, GM1, were 2H-labelled at C-6 (the hydroxymethyl moiety) of their single terminal galactosyl residues. Each deuterated glycosphingolipid was incorporated at a biologically relevant low concentration into multibilayers of 1-palmitoyl-2-oleoylphosphatidylcholine (POPC). 2H-NMR spectra of aqueous dispersions of GalCer-POPC in the liquid crystal phase were characteristic of restricted headgroup motion (ordering) with effective axial symmetry. The degree of headgroup ordering was analogous to that of GalCer in pure aqueous multibilayers (Skarjune, R. and Oldfield, E. (1979) Biochim. Biophys. Acta 556, 208-218). In the case of GM1, 2H-labelled in the terminal galactose residue of the pentasaccharide headgroup, the 2H-NMR spectra were remarkably like those of the simple glycolipid, GalCer. This suggests substantial restriction of motion about the glycosidic and sugar-ceramide bonds of the complex GM1 headgroup, and that both lipids have comparable degrees of orientational averaging (fluctuation) about the bilayer normal. The result is the first direct demonstration that headgroup orientational order can exist for a complex glycolipid incorporated into 'fluid' bilayer membranes. Such behaviour argues for the possibility of modulation of membrane receptor properties through surface effects on average headgroup orientation and conformation.
半乳糖神经酰胺（GalCer）和神经节苷脂GM1在其单个末端半乳糖基残基的C-6（羟甲基部分）处用2H标记。每种氘代糖鞘脂以生物学相关的低浓度掺入1-棕榈酰-2-油酰磷脂酰胆碱（POPC）的多层膜中。液晶相的GalCer-POPC水分散体的2H-NMR光谱具有有效轴向对称性的受限头部基团运动（有序）特征。头部基团的有序程度与纯水性多层膜中的GalCer相似（Skarjune，R.和Oldfield，E.（1979年）Biochim. Biophys. Acta 556，208-218）。对于在五糖头部基团的末端半乳糖残基中标记有2H的GM1，2H-NMR光谱与简单糖脂GalCer的光谱非常相似。这表明复杂的GM1头部基团的糖苷键和糖神经酰胺键周围的运动受到很大限制，并且两种脂质在双层法线周围具有相当程度的取向平均（波动）。该结果首次直接证明了掺入“流体”双层膜中的复杂糖脂可以存在头部基团取向有序。这种行为表明通过对平均头部基团取向和构象的表面效应来调节膜受体特性的可能性。
