title: Exploring the energy profile of human IgG/rat anti-human IgG interactions by dynamic force spectroscopy.
abstract: Interactions between antibody and antigen molecules play essential roles in biological recognition processes as well as medical diagnosis. Therefore, an understanding of the underlying mechanism of antibody-antigen interactions at the single molecular level would be beneficial. In the present study, human immunoglobulin (IgG) tethered cantilevers and rat anti-human IgG functionalized gold surfaces were fabricated by using self-assembled monolayers method. Dynamic force spectroscopy was employed to characterize the interactions between human (IgG) and rat anti-human IgG at the single-molecule level. The unbinding forces were determined to be 44.6 ± 0.8, 65.8 ± 3.0, 108.1 ± 4.1, 131.1 ± 11.2, 149.5 ± 4.7, 239.5 ± 3.1 and 294.7 ± 7.7 pN with ramping loading rates of 514, 1,127, 3,058, 7,215, 15,286, 31,974 and 50,468 pN s(-1), respectively. In addition, the unbinding forces were found to be increasing with the logarithm of apparent loading rates in a linear way. Fitting data group resulted in two distinct linear parts, suggesting there are two energy barriers. The corresponding distances in the bound and transition states (x ( β )) and the dissociation rates (K ( off )) were calculated to be 0.129 ± 0.006 nm, 3.986 ± 0.162 s(-1) for the outer barrier and 0.034 ± 0.001 nm, 36.754 ± 0.084 s(-1) for the inner barrier. Such findings hold promise of screening novel drugs and discerning different unbinding modes of biological molecules.
authors.affiliation: Key Laboratory of Biorheological Science and Technology, Ministry of Education, and Institute of Biochemistry and Biophysics, College of Bioengineering, Chongqing University, Chongqing, 400044, China.
authors.forename: Zhengjian
authors.initials: Z
authors.lastname: Lv
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
authors.forename: Guoping
authors.initials: G
authors.lastname: Chen
mesh_terms: D000818:Animals; D000888:Antibodies, Anti-Idiotypic / Q000737:chemistry / Q000276:immunology*; D055910:Antibodies, Immobilized / Q000737:chemistry / Q000276:immunology; D000937:Antigen-Antibody Reactions; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology*; D018625:Microscopy, Atomic Force / Q000379:methods*; D025941:Protein Interaction Mapping / Q000379:methods; D051381:Rats; D013816:Thermodynamics
chemical_list: D000888:Antibodies, Anti-Idiotypic; D055910:Antibodies, Immobilized; D007074:Immunoglobulin G; C048844:anti-IgG