Molecular arrangement of adsorbed fibrinogen molecules characterized by specific monoclonal antibodies and a surface plasmon resonance sensor

The exploitation of surface plasmon resonance optical sensor for the study of the accessibility of distinct domains of immobilized fibrinogen molecules and the evaluation of the fibrinogen arrangement is reported. By investigation of the interactions of sensor surface-bound fibrinogen with various specific monoclonal antibodies it has been found that density, orientation, and accessibility of the individual fibrinogen domains of surface-bound fibrinogen depend on the concentration of fibrinogen in solution during the adsorption process. At low fibrinogen surface density the majority of molecules seem to be adsorbed side-on (lying on the surface). At high fibrinogen density the molecules are adsorbed end-on (standing on the surface). The experimental data suggest that the distal ends of the (adsorbed) fibrinogen molecule (containing polymerisation sites) are oriented anti-parallel to each other, proving off-axis location of the distal end domains. (C) 1998 Elsevier Science S.A. All rights reserved.