Adsorption of the protein antigen myoglobin affects the binding of conformation-specific monoclonal antibodies

Five monoclonal antibodies against sperm whale myoglobin have been used to investigate the physical state of the antigen adsorbed onto a polydimethylsiloxane surface. The binding of each antibody is sensitive to the antigen's conformation in solution while the locations of the antigenic sites on the myoglobin molecule for three of the antibodies have been determined (Berzofsky, J.A., G.K. Buckenmeyer, G. Hicks, F.R.N. Gurd, R.J. Feldmann, and J. Minna. 1982. J. Biol. Chem. 257:3189–3198). The binding of the fluorescein isothiocyanate-labeled IgG and Fab antibodies to previously adsorbed myoglobin has been observed using total internal reflection fluorescence. Three of the antibodies bind specifically to surface-adsorbed myoglobin with affinities at least 50% relative to myoglobin in solution whereas two of the antibodies show affinities for the surface-adsorbed myoglobin diminished by at least two orders of magnitude relative to myoglobin in solution. The specific loss of certain antigenic determinants on the adsorbed myoglobin, coupled with the retention of others, indicates a nonrandom adsorption of the myoglobin molecules