title: High-resolution single-molecule recognition imaging of the molecular details of ricin-aptamer interaction.
abstract: 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.
authors.affiliation: Single Molecule Study Laboratory, Faculty of Engineering and Nanoscale Science and Engineering Center, University of Georgia, Athens, Georgia 30602, United States.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Cunlan
authors.initials: C
authors.lastname: Guo
authors.forename: Mengmeng
authors.initials: M
authors.lastname: Zhang
authors.forename: Bosoon
authors.initials: B
authors.lastname: Park
authors.forename: Bingqian
authors.initials: B
authors.lastname: Xu
mesh_terms: D000906:Antibodies / Q000276:immunology; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D006046:Gold / Q000737:chemistry; D055767:Immobilized Proteins / Q000737:chemistry / Q000378:metabolism; D018625:Microscopy, Atomic Force; D011485:Protein Binding; D012276:Ricin / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism; D013388:Succinimides; D013499:Surface Properties
chemical_list: D000906:Antibodies; D052157:Aptamers, Nucleotide; D055767:Immobilized Proteins; D013388:Succinimides; D006046:Gold; D012276:Ricin; C001426:N-hydroxysuccinimide