The elderberry (Sambucus nigra L.) bark lectin recognizes the Neu5Ac(alpha 2-6)Gal/GalNAc sequence.
The elderberry (Sambucus nigra L.) bark lectin recognizes the Neu5Ac(alpha 2-6)Gal/GalNAc sequence.
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DOI：
10.1016/s0021-9258(19)75677-4
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发表时间：
1987-02
期刊：
影响因子：
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通讯作者：
N. Shibuya;I. Goldstein;W. Broekaert;M. Nsimba-Lubaki;B. Peeters;W. Peumans
中科院分区：
文献类型：
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作者：
N. Shibuya;I. Goldstein;W. Broekaert;M. Nsimba-Lubaki;B. Peeters;W. Peumans
接骨木植物凝集素的碳水化合物结合特性研究采用定量沉淀、半抗原抑制和平衡透析技术对SNA树皮进行了研究。纯化的SNA可析出高度唾液化的糖蛋白，如胎蛋白、类口腔粘液蛋白和羊颌下黏液蛋白，但不能析出它们的亚洲动物衍生物。半抗原抑制实验表明，D-Gal和D-GalNAc都是sna -糖蛋白沉淀的弱抑制剂，而New5Ac和Neu5Gc都不是抑制剂。含有末端Neu5Ac(α 2-6)Gal序列的一系列寡糖显示出极高的抑制效力（比Gal强1600 - 10000倍）。另一方面，具有Neu5Ac(α 2-3)Gal连接的低聚糖的抑制作用仅为Gal的30-80倍，因此对2,6连接的异构体表现出明显的偏好。半抗原对Gal及其外显体的抑制表明，d -吡喃糖环C-3上的赤道羟基和C-4上的轴向羟基是结合的严格要求。Neu5Ac残基通过选择性高酸盐氧化其甘油侧链将其转化为7碳类似物，随后NaBH4还原，完全破坏了胎儿蛋白和orosomucoid与SNA沉淀的能力。此外，同样处理Neu5Ac（α - 2-3）乳醇也消除了其抑制沉淀反应的能力，这表明NBu5Ac的甘油侧链（特别是C-8和/或C-9部分）是SNA的重要决定因素。各种糖苷与β -连接的非极性苷元的抑制效力增强，表明在碳水化合物结合位点附近存在亲水性相互作用区域。用[3H] Neu5Ac（α 2-6）乳糖醇作为配体进行平衡透析的结果显示，在这种四聚体糖蛋白凝集素中存在两个等效的、不相互作用的碳水化合物结合位点（Ka = 3.9 X 10(5) M-1）。
Carbohydrate binding properties of a new plant lectin isolated from elderberry (Sambucus nigra L.) (SNA) bark were studied using the techniques of quantitative precipitation, hapten inhibition, and equilibrium dialysis. Purified SNA precipitates highly sialylated glycoproteins such as fetuin, orosomucoid, and ovine submaxillary mucin, but not their asialo derivatives. Hapten inhibition experiments showed that both D-Gal and D-GalNAc are weak inhibitors of SNA-glycophorin precipitation, but neither New5Ac nor Neu5Gc is an inhibitor. A series of oligosaccharides which contain the terminal Neu5Ac(alpha 2-6)Gal sequence showed an extremely high inhibitory potency (1,600-10,000 times more inhibitory than Gal). On the other hand, oligosaccharides with the Neu5Ac(alpha 2-3)Gal linkage were only 30-80 times more inhibitory than Gal, thus showing a marked preference for the 2,6-linked isomer. Hapten inhibition with Gal and its epimers suggested that the equatorial OH at C-3 and the axial OH at C-4 of the D-pyranose ring are strict requirements for binding. Conversion of the Neu5Ac residue to its 7-carbon analogue by selective periodate oxidation of its glyceryl side chain, followed by NaBH4 reduction, completely destroyed the ability of fetuin and orosomucoid to precipitate with SNA. Moreover, the same treatment of Neu5Ac(alpha 2-3)lactitol also abolished its ability to inhibit the precipitation reaction, suggesting that the glyceryl side chain of NBu5Ac (especially the C-8 and/or C-9 portion) is an important determinant for SNA. The increased inhibitory potency of various glycosides with beta-linked nonpolar aglycons suggested the presence of a hydrophibic interacting region adjacent to the carbohydrate binding site. The results of equilibrium dialysis using [3H] Neu5Ac(alpha 2-6)lactitol as ligand showed the presence of two equivalent, noninteracting carbohydrate binding sites in this tetrameric glycoprotein lectin (Ka = 3.9 X 10(5) M-1).