Dependence of avidity on linker length for a bivalent ligand-bivalent receptor model system.
Dependence of avidity on linker length for a bivalent ligand-bivalent receptor model system.
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DOI：
10.1021/ja2073033
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发表时间：
2012-01-11
影响因子：
15
通讯作者：
Whitesides GM
中科院分区：
文献类型：
--
作者：
Mack ET;Snyder PW;Perez-Castillejos R;Bilgiçer B;Moustakas DT;Butte MJ;Whitesides GM
本文描述了一种合成的碳酸酐酶二聚体，和一系列不同长度的二价磺酰胺配体（完全延伸的配体末端之间为25至69个碱基），作为模型系统用于检查二价抗体与抗原的结合。基于分析超离心和荧光结合的测定表明，该系统形成环状的非共价复合物，其化学计量为一个二价配体与一个二聚体。该二聚体以低皮摩尔亲合力（K亲合力= 3 - 40 pM）结合一系列二价配体。结构上类似的单价配体结合到二聚体的一个活性位点，Kdmono = 16 nM。因此，二价缔合比单价缔合显著更强（Kd单/Kd davidity范围为约500至5000单位）。我们从这些结果中推断，并通过将这些结果与先前的研究进行比较，抗体中的二价可以导致比单价缔合更紧密的缔合（尽管观察到的二价缔合比从理论预测的最简单水平-约0.002 pM的Kdavidity和Kdmono/Kdavidity约8 × 106无单位-预测的弱得多）。
This paper describes a synthetic dimer of carbonic anhydrase, and a series of bivalent sulfonamide ligands with different lengths (25 to 69 Å between the ends of the fully extended ligands), as a model system to use in examining the binding of bivalent antibodies to antigens. Assays based on analytical ultracentrifugation and fluorescence binding indicate that this system forms cyclic, noncovalent complexes with a stoichiometry of one bivalent ligand to one dimer. This dimer binds the series of bivalent ligands with low picomolar avidities (Kdavidity = 3 – 40 pM). A structurally analogous monovalent ligand binds to one active site of the dimer with Kdmono = 16 nM. The bivalent association is thus significantly stronger (Kdmono/Kdavidity ranging from ~500 to 5000 unitless) than the monovalent association. We infer from these results, and by comparison of these results to previous studies, that bivalency in antibodies can lead to associations much tighter than monovalent associations (although the observed bivalent association is much weaker than predicted from the simplest level of theory—predicted Kdavidity of ~ 0.002 pM and Kdmono/Kdavidity ~ 8 × 106 unitless).