13C NMR studies of wheat germ agglutinin interactions with N-acetylglucosamine at a magnetically oriented bilayer surface.
13C NMR studies of wheat germ agglutinin interactions with N-acetylglucosamine at a magnetically oriented bilayer surface.
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麦芽凝集素与 N-乙酰氨基葡萄糖在磁性取向双层表面相互作用的 13C NMR 研究。
DOI：
10.1021/bi00199a042
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发表时间：
1994
期刊：
影响因子：
2.9
通讯作者：
Prestegard,JH
中科院分区：
文献类型：
--
作者：
Hare,BJ;Rise,F;Aubin,Y;Prestegard,JH
摘要：利用核磁共振波谱技术，在定向膜系统中研究了合成的13c标记糖脂受体的取向及其与植物凝集素小麦胚芽凝集素的相互作用。合成了一系列的2-[1,2 - 13c2]乙酰氨基-2-脱氧-/3- d -葡萄糖吡喃苷，在头基和将受体固定在双分子层上的烷基链之间具有0到4个亲水性乙氧基单元。13C羰基的化学位移各向异性和标记碳之间的13C-13C偶极耦合提供了定向膜系统中受体头群的取向和动力学信息。结果表明，具有两个、三个或四个乙氧基单位的受体在定向双分子层中呈现出各向同性，而具有零或一个乙氧基单位的受体则在定向双分子层中呈现出明显的有序性。对于具有0和1个乙氧基单元的受体，确定了与测量光谱参数一致的平均取向，并发现与分子模型的低能构象一致。当将植物凝集素小麦胚芽凝集素添加到样品中时，只有将头基与烷基链分开的具有两个、三个或四个乙氧基单位的受体显示出被凝集素结合的证据。虽然13c标记的共振在蛋白质结合时变宽，但偶极偶联和化学位移各向异性没有变化，表明蛋白质结合减缓了头群的运动，但平均取向和整体顺序变化不大。竞争研究表明，没有一种凝集素/受体复合物比凝集素和a -乙酰氨基葡萄糖在溶液中的复合物更稳定。这些结果表明，膜不能稳定小麦胚芽凝集素与这些细胞表面受体的相互作用。此外，分子模型表明，零间隔和一间隔受体可能不会结合小麦胚芽凝集素，因为这些受体中a -乙酰基的取向会导致凝集素/受体复合物与膜之间的显著空间接触。膜表面的碳水化合物和蛋白质之间的相互作用介导了多种生物过程。这包括细菌或病毒感染宿主细胞的第一步（Lingwood, 1992; Sharon & Lis, 1993），胚胎发生期间细胞的分化（Feizi, 1985），以及致癌细胞转化（Hakomori, 1991）。来自植物的可溶性凝集素是第一个被发现的糖特异性结合蛋白，它们与糖相互作用的分子基础及其生物学功能仍然是研究的活跃领域（Lis & Sharon, 1991; Hoekstra & Duzgunes, 1989）。最近，在包括人类在内的哺乳动物中发现了凝集素和具有凝集素样结构域的蛋白质。这些分子已知的功能包括糖蛋白的内噬作用，补体介导的病原体裂解，以及最近表征的作为炎症反应一部分的白细胞与内皮细胞的粘附（Drickamer, 1988,1993; Mayadasetal）。, 1993;拉斯基,1992;休斯,1992)。越来越多的证据表明，细胞表面碳水化合物的构象性质是
Revised Manuscript Received June 15, 1994* abstract: The orientation of synthetic 13C-labeled glycolipid receptors and their interaction with the plant lectin wheat germ agglutinin have been studied in an oriented membrane system using NMR spectroscopy. A series of 2-[1, 2-13C2] acetamido-2-deoxy-/3-D-glucopyranosides were synthesized with between zero and four hydrophilic ethoxy units between the headgroup and an alkyl chain which anchors the receptors in the bilayers. The chemicalshift anisotropy of the 13C carbonyl and a 13C-13C dipolar coupling between the labeled carbons provide information aboutthe orientation and dynamics of the receptor headgroup in oriented membrane systems. It was found that the headgroups of the receptors with two, three, or four ethoxy units appeared isotropic when incorporated in the oriented bilayers, but those of the receptors with zero or one ethoxy units were significantly ordered by the bilayers. The average orientations consistent with measured spectral parameters were determined for the receptors with zero and one ethoxy units and were found to coincide with low-energy conformations from molecular modeling. When the plant lectin wheat germ agglutinin was added to the sample, only the receptors with two, three, or four ethoxy units separating the headgroup from the alkyl chain showed evidence of binding by the lectin. Although the 13C-labeled resonances broadened when the protein bound, no changes in dipolar couplings or chemical shift anisotropies could be detected, suggesting that the motion of the headgroup was slowed by protein binding, but average orientation and overall order changed little. Competition studies demonstrated that none of the lectin/receptor complexes are more stable than the complex of the lectin and A-acetylglucosamine in solution. These results suggest that the membrane does not stabilize the interactions of wheat germ agglutinin with these cell-surface receptors. Furthermore, molecular modeling demonstrates that the zero-and one-spacer receptors may not bind wheat germ agglutinin because the orientations of the A-acetyl groups in these receptors would result in significant steric contacts between the lectin/receptor complex and the membrane.A wide variety of biological processes are mediated by interactions between carbohydrates and proteins at the surfaces of membranes. These include the initial step in infection of a host cell by bacteria or viruses (Lingwood, 1992; Sharon & Lis, 1993), differentiation of cells during embryogenesis (Feizi, 1985), and oncogenic cellular transformation (Hakomori, 1991). Soluble lectinsfrom plants were the first sugar-specific binding proteins to be discovered, and the molecular basis for their interactions with sugars and their biological functions remain active areas of research (Lis & Sharon, 1991; Hoekstra & Duzgunes, 1989). More recently, lectins and proteins with lectin-like domainshave been discovered in mammals, including humans. The known functions of these molecules include endocytosis of glycoproteins, complement-mediated lysis of pathogens as well as the recently characterized adhesion of leukocytes to endothelial cells as part of the inflammatory response (Drickamer, 1988, 1993; Mayadasetal., 1993; Lasky, 1992; Hughes, 1992). Increasing evidencesuggests that the conformational properties of cell-surface carbohydrates are
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DOI：
10.1016/s0021-9258(18)43638-1
发表时间：
1980
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
R. Hampton;R. Holz;I. Goldstein
通讯作者：
I. Goldstein
DOI：
--
发表时间：
1992
期刊：
影响因子：
--
作者：
C. Sanders;J. Prestegard
通讯作者：
J. Prestegard
DOI：
10.1016/0005-2736(76)90037-7
发表时间：
1976
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
W. R. Redwood;T. Polefka
通讯作者：
T. Polefka
影响因子：
56.9
作者：
KETCHEM, RR;HU, W;CROSS, TA
通讯作者：
CROSS, TA
洗涤剂溶解的 M13 外壳蛋白中酰胺 1H 和 15N NMR 共振的归属：外壳蛋白二聚体的模型。
影响因子：
2.9
作者：
G. D. Henry;B. Sykes
通讯作者：
B. Sykes