title: Binding kinetics of an antibody against HIV p24 core protein measured with real-time biomolecular interaction analysis suggest a slow conformational change in antigen p24.
abstract: The interaction between HIV core protein p24 and the murine monoclonal antibody CB-4/1 or its Fab fragment showed unusual kinetics. Recombinant p24 was immobilised in a hydrophilic carboxymethyldextran matrix. At high concentration of CB-4/1 Fab the association of the antigen-antibody complex proceeds in two phases, while dissociation is mono-exponential. The antigen has a 'memory', i.e. shortly after dissociation of Fab-antigen complex the fast association phase is enhanced. Biphasic association was also found in solution. Experiments suggest a reversible change of binding properties in the epitope region with an overall time constant of about 100 s at room temperature. Intermediate steps with faster time constants must be involved. Slow conformational changes of p24 seem to be the most probable explanation. A simple model that provides a quantitative description of this process could not be found. Real-time analysis of antibody binding by surface plasmon resonance is a powerful method for studying such changes in the time domain of a few seconds to a few minutes.
authors.affiliation: Department of Medical Immunology, Humboldt University Berlin, Medical School (Charité), Germany.
authors.forename: R W
authors.initials: RW
authors.lastname: Glaser
authors.forename: G
authors.initials: G
authors.lastname: Hausdorf
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry; D000915:Antibody Affinity; D001666:Binding Sites, Antibody; D001667:Binding, Competitive / Q000276:immunology; D015374:Biosensing Techniques; D015483:HIV Antibodies / Q000737:chemistry*; D016655:HIV Core Protein p24 / Q000737:chemistry* / Q000276:immunology*; D006801:Humans; D007118:Immunoassay; D007700:Kinetics; D018448:Models, Immunological; D008969:Molecular Sequence Data; D010455:Peptides / Q000276:immunology / Q000494:pharmacology; D011487:Protein Conformation; D012996:Solutions
chemical_list: D000911:Antibodies, Monoclonal; D015483:HIV Antibodies; D016655:HIV Core Protein p24; D010455:Peptides; D012996:Solutions