title: Secondary force-mediated perturbations of antifluorescein monoclonal antibodies 4-4-20 and 9-40 as determined by circular dichroism.
abstract: Secondary forces have been defined as those interactions between antibody and antigen that occur external to the antibody active site. Previous investigations indicated that non-active-site secondary interactions can modulate immune complex stability and may influence antibody variable domain conformation and/or dynamics. To assess secondary force-induced perturbations of monoclonal antibodies 4-4-20 and 9-40 a series of monofluoresceinated peptides was reacted and the various interactions analyzed by circular dichroism (CD). The mAbs 4-4-20 and 9-40 vary by nearly 1000-fold in their respective affinities for the fluorescein ligand, yet both immunoglobulins are highly related at the primary structural (idiotype) level. Near-UV CD spectra were evaluated as well as the induced optical activity (visible CD) of the antibody-bound fluorescein moiety when covalently attached to various peptide carriers. Comparative spectral studies revealed significant differences in the near-UV CD spectra of mAbs 9-40 and 4-4-20 relative to the various peptide antigens and to one another. CD spectra were interpreted as reflecting differential secondary force-induced perturbations of the antibody variable domains as well as intrinsic differences between the two mAbs.
authors.affiliation: University of Illinois, Department of Microbiology, Urbana 61801, USA.
authors.forename: M E
authors.initials: ME
authors.lastname: Mummert
authors.forename: E W
authors.initials: EW
authors.lastname: Voss
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry*; D000915:Antibody Affinity; D000936:Antigen-Antibody Complex / Q000737:chemistry; D002942:Circular Dichroism; D003287:Contrast Media; D019793:Fluorescein; D011487:Protein Conformation
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D003287:Contrast Media; D019793:Fluorescein