Khan M I, Mandal D K, Brewer C F
Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York 10461.
Carbohydr Res. 1991 Jun 25;213:69-77. doi: 10.1016/s0008-6215(00)90599-8.
Certain oligomannose-type glycopeptides have been previously shown to be bivalent for binding to concanavalin A and capable of precipitating the lectin by forming homogeneous cross-linked lattices [L. Bhattacharyya, M. I. Khan, and C.F. Brewer, Biochemistry, 27 (1988) 8762-8767]. In the present study, the effect of protein environment on the binding properties of an oligomannose-type oligosaccharide has been examined through quantitative precipitation analysis of the interactions of concanavalin A (Con A) with the soybean (Glycine max) agglutinin (SBA), which is a tetrameric glycoprotein possessing a single Man9-oligomannose chain per monomer. The results showed that SBA forms two different types of cross-linked complexes with tetrameric Con A, depending on the relative ratio of the two molecules in solution. At a concentration of one equivalent or less, SBA forms a 1:1 complex with Con A. At concentrations exceeding one equivalent, SBA forms a 2:1 complex with Con A. However, SBA forms only 1:1 cross-linked complexes with dimeric forms of Con A, such as acetyl- and succinyl-Con A. The results demonstrated that the total valency of the carbohydrate of SBA is a function of both the quaternary structure of Con A, as well as the relative ratio of SBA to Con A. In addition, the individual Man9-oligosaccharide, which as a glycopeptide is bivalent for binding to Con A, expresses univalency when present on the protein matrix of SBA.
某些低聚甘露糖型糖肽先前已被证明对伴刀豆球蛋白A具有二价结合能力，并能够通过形成均匀的交联晶格使该凝集素沉淀[L. 巴塔查里亚、M. I. 汗和C. F. 布鲁尔，《生物化学》，27 (1988) 8762 - 8767]。在本研究中，通过对伴刀豆球蛋白A（Con A）与大豆（Glycine max）凝集素（SBA）相互作用的定量沉淀分析，研究了蛋白质环境对低聚甘露糖型寡糖结合特性的影响，SBA是一种四聚体糖蛋白，每个单体含有一条Man9 - 低聚甘露糖链。结果表明，SBA与四聚体Con A形成两种不同类型的交联复合物，这取决于溶液中两种分子的相对比例。在当量浓度或更低时，SBA与Con A形成1:1复合物。在超过当量浓度时，SBA与Con A形成2:1复合物。然而，SBA仅与Con A的二聚体形式，如乙酰化和琥珀酰化Con A形成1:1交联复合物。结果表明，SBA碳水化合物的总价数是Con A四级结构以及SBA与Con A相对比例的函数。此外，单个Man9 - 寡糖作为糖肽对Con A具有二价结合能力，但当存在于SBA的蛋白质基质上时表现为单价。
