Energy landscape of chelated uranyl:: Antibody interactions by dynamic force spectroscopy
Energy landscape of chelated uranyl:: Antibody interactions by dynamic force spectroscopy
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DOI：
10.1529/biophysj.106.098129
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发表时间：
2007-07-01
影响因子：
3.4
通讯作者：
Pellequer, Jean-Luc
中科院分区：
文献类型：
--
作者：
Odorico, Michael;Teulon, Jean-Marie;Pellequer, Jean-Luc
我们使用动态力谱（DFS）来探索螯合铀酰化合物与针对铀酰-二羧基-菲罗啉配合物的单克隆抗体之间相互作用的能量格局。我们沿离解坐标估计了势能势垒宽度和相关的热力学速率常数。利用原子力显微镜，在螯合配体中有或没有铀酰离子的四种不同的实验设置，我们区分了铀酰化合物与抗体的结合亲和力的特异性和非特异性结合。我们系统的力加载速率从15到26,400 pN/s不等。结果显示，在最可能的解结合力与加载速率的对数的图中有两种制度，揭示了两个（至少）激活屏障的存在。对DFS的分析表明，在两种情况下都存在平行的多价结合。我们还建立了抗体可变片段的分子模型，并使用计算图形将螯合铀酰离子停靠到结合口袋中。结构分析使我们假设这两种机制源于两种相互作用模式：第一种机制对应于宽度为0.5 +/- 0.2埃的能量势垒，推断铀酰离子从其第一配位壳（Asp残基）解离；第二个具有更宽的能垒宽度（3.9 +/- 0.3埃）推断出与抗体解离的整个螯合化合物。我们的研究突出了DFS实验在解剖蛋白质-金属化合物相互作用方面的敏感性。
We used dynamic force spectroscopy (DFS) to explore the energy landscape of interactions between a chelated uranyl compound and a monoclonal antibody raised against the uranyl-dicarboxy-phenanthroline complex. We estimated the potential energy barrier widths and the relevant thermodynamic rate constants along the dissociation coordinate. Using atomic force microscopy, four different experimental setups with or without the uranyl ion in the chelate ligand, we have distinguished specific and nonspecific binding in the binding affinity of the uranyl compound to the antibody. The force loading rates for our system were measured from 15 to 26,400 pN/s. The results showed two regimes in the plot of the most probable unbinding force versus the logarithm of the loading rate, revealing the presence of two ( at least) activation barriers. Analyses of DFS suggest parallel multivalent binding present in either regime. We have also built a molecular model for the variable fragment of the antibody and used computational graphics to dock the chelated uranyl ion into the binding pocket. The structural analysis led us to hypothesize that the two regimes originate from two interaction modes: the first one corresponds to an energy barrier with a very narrow width of 0.5 +/- 0.2 angstrom, inferring dissociation of the uranyl ion from its first coordination shell (Asp residue); the second one with a broader energy barrier width ( 3.9 +/- 0.3 angstrom) infers the entire chelate compound dissociated from the antibody. Our study highlights the sensitivity of DFS experiments to dissect protein-metal compound interactions.