Negative cooperativity associated with binding of multivalent carbohydrates to lectins. thermodynamic analysis of the "multivalency effect"
Negative cooperativity associated with binding of multivalent carbohydrates to lectins. thermodynamic analysis of the "multivalency effect"
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DOI：
10.1021/bi015830j
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发表时间：
2002-01-29
期刊：
影响因子：
2.9
通讯作者：
Brewer, CF
中科院分区：
文献类型：
--
作者：
Dam, TK;Roy, R;Brewer, CF
我们以前的研究表明，等温滴定微量热法（ITC）可用于测定一系列合成的多价碳水化合物与Man/Glc特异性凝集素伴刀豆球蛋白A（ConA）和大花山龙眼凝集素（DGL）结合的热力学[Dam，T. K.，罗伊河，巴西-地达斯，S。K.，Oscarson，S.和Brewer，C. F.（2000）J.Biol.Chem.275，14223-14230]。两种凝集素的多价碳水化合物的较高亲和力被证明是由于它们相对于单价类似物的结合贡献的更大的正熵。在本研究中，ITC数据从我们以前的报告结合的二，三，四价碳水化合物类似物具有末端3，6-二-O-（α-D-吡喃甘露糖基）-α-D-吡喃甘露糖苷残基ConA和DGL进行希尔图分析。单价甲基3，6-二-O-（α-D-吡喃甘露糖基）-α-D-吡喃甘露糖苷与ConA和DGL结合的Hill图是线性的，斜率接近1.0，表明蛋白质中缺乏结合协同性和变构转换。然而，希尔图的结合的二，三，和四价的三甘露糖苷类似物的两种凝集素是曲线的切线斜率低于1.0，表明增加的负协同性后，结合的类似物的凝集素。曲线Hill图与凝集素分子与类似物的碳水化合物表位顺序结合后多价类似物的亲和力和功能价降低一致。以下文件[大坝，T。K.，罗伊河，巴西-地佩奇，D.，和Brewer，C. F.（2002）Biochemistry，41，1359-1363]提供了多价碳水化合物在凝集素分子顺序结合后亲和力常数降低的直接证据。
Our previous study demonstrated that isothermal titration microcalorimetry (ITC) could be used to determine the thermodynamics of binding of a series of synthetic multivalent carbohydrates to the Man/Glc-specific lectins concanavalin A (ConA) and Dioclea grandiflora lectin (DGL) [Dam, T. K., Roy, R., Das, S. K., Oscarson, S. and Brewer, C. F. (2000) J. Biol. Chem. 275, 14223-14230]. The higher affinities of the multivalent carbohydrates for the two lectins were shown to be due to their greater positive entropy of binding contributions relative to monovalent analogues. In the present study, ITC data from our previous report for binding of di-, tri-, and tetravalent carbohydrate analogues possessing terminal 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside residues to ConA and DGL were subjected to Hill plot analysis. Hill plots of the binding of monovalent methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside to ConA and DGL are linear with slopes near 1.0, demonstrating a lack of binding cooperativity and allosteric transitions in the proteins. However, Hill plots for the binding of the di-, tri-, and tetravalent trimannoside analogues to both lectins are curvilinear with decreasing tangent slopes below 1.0, indicating increasing negative cooperativity upon binding of the analogues to the lectins. The curvilinear Hill plots are consistent with decreasing affinity and functional valencies of the multivalent analogues upon sequential binding of lectin molecules to the carbohydrate epitopes of the analogues. The following paper [Dam, T. K., Roy, R., Page, D., and Brewer, C. F. (2002) Biochemistry, 41, 1359-1363] provides direct evidence of the decreasing affinity constants of multivalent carbohydrates upon sequential binding of lectin molecules.