Single Molecule Study Laboratory, Faculty of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, Georgia 30602, United States.
J Phys Chem B. 2012 May 3;116(17):5316-22. doi: 10.1021/jp301765n. Epub 2012 Apr 19.
We studied the molecular details of DNA aptamer-ricin interactions. The toxic protein ricin molecules were immobilized on a Au(111) surface using a N-hydroxysuccinimide (NHS) ester to specifically react with lysine residues located on the ricin B chains. A single ricin molecule was visualized in situ using the AFM tip modified with an antiricin aptamer. Computer simulation was used to illustrate the protein and aptamer structures, the single-molecule ricin images on a Au(111) surface, and the binding conformations of ricin-aptamer and ricin-antibody complexes. The various ricin conformations on a Au(111) surface were caused by the different lysine residues reacting with the NHS ester. It was also observed that most of the binding sites for aptamer and antibody on the A chains of ricin molecules were not interfered by the immobilization reaction. The different locations of the ricin binding sites to aptamer and antibody were also distinguished by AFM recognition images and interpreted by simulations.
我们研究了 DNA 适体-蓖麻毒素相互作用的分子细节。使用 N-羟基琥珀酰亚胺 (NHS) 酯将毒性蛋白蓖麻毒素分子固定在 Au(111)表面上，以特异性地与位于蓖麻毒素 B 链上的赖氨酸残基反应。使用修饰有抗蓖麻毒素适体的 AFM 尖端原位可视化单个蓖麻毒素分子。计算机模拟用于说明蛋白质和适体结构、Au(111)表面上的单个分子蓖麻毒素图像以及蓖麻毒素-适体和蓖麻毒素-抗体复合物的结合构象。由于 NHS 酯与不同的赖氨酸残基反应，导致了在 Au(111)表面上的各种蓖麻毒素构象。还观察到，在蓖麻毒素分子 A 链上，适体和抗体的大部分结合位点不受固定化反应的干扰。蓖麻毒素与适体和抗体结合的不同位置也通过 AFM 识别图像区分，并通过模拟进行解释。
