Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
J Am Chem Soc. 2011 May 4;133(17):6636-41. doi: 10.1021/ja110700x. Epub 2011 Apr 7.
Phage display is widely used for the selection of target-specific peptide sequences. Presentation of phage peptides on a multivalent platform can be used to (partially) restore the binding affinity. Here, we present a detailed analysis of the effects of valency, linker choice, and receptor density on binding affinity of a multivalent architecture, using streptavidin (SA) as model multivalent receptor. For surfaces with low receptor densities, the SA binding affinity of multivalent dendritic phage peptide constructs increases over 2 orders of magnitude over the monovalent species (e.g., K(d,mono) = 120 μM vs K(d,tetra) = 1 μM), consistent with previous work. However, the affinity of the SA-binding phage presenting the exact same peptides was 16 pM when dense receptor surfaces used for initial phage display were used in assays. The phage affinity for SA-coated surfaces weakens severely toward the nanomolar regime when surface density of SA is decreased. A similarly strong dependence in this respect was observed for dendritic phage analogues. When presented with a dense SA-coated surface, dendrimer display affords up to a 10(4)-fold gain in affinity over the monovalent peptide. The interplay between ligand valency and receptor density is a fundamental aspect of multivalent targeting strategies in biological systems. The perspective offered here suggests that in vivo targeting schemes might best be served to conduct ligand selection under physiologically relevant receptor density surfaces, either by controlling the receptor density placed at the selection surface or by using more biologically relevant intact cells and tissues.
噬菌体展示技术被广泛用于筛选针对特定靶标的肽序列。在多价平台上展示噬菌体肽可以（部分）恢复结合亲和力。在这里，我们使用链霉亲和素（SA）作为模型多价受体，对多价结构中价数、连接子选择和受体密度对结合亲和力的影响进行了详细分析。对于受体密度较低的表面，多价树突状噬菌体肽构建体的 SA 结合亲和力比单价物种增加了 2 个数量级以上（例如，K(d,mono) = 120 μM 对 K(d,tetra) = 1 μM），与之前的工作一致。然而，当在测定中使用最初用于噬菌体展示的密集受体表面时，展示相同肽的 SA 结合噬菌体的亲和力为 16 pM。当 SA 的表面密度降低时，噬菌体对 SA 涂覆表面的亲和力严重减弱到纳摩尔级。在这方面，树突状噬菌体类似物也观察到了类似的强依赖性。当与密集的 SA 涂覆表面接触时，树枝状噬菌体展示相对于单价肽提供了高达 10^4 倍的亲和力增益。配体价数和受体密度之间的相互作用是生物系统中多价靶向策略的一个基本方面。这里提供的观点表明，在体内靶向方案中，最好在生理相关受体密度的表面下进行配体选择，要么通过控制选择表面上的受体密度，要么通过使用更具生物学相关性的完整细胞和组织。
