[Study of the polymerization of fibrin using monoclonal antibodies 2D-2A and their Fab-fragments].

It has been shown that monAb's 2d-2a and their Fab-fragments are specific and effective inhibitors of fibrinogen clotting. Only one IgG molecule of monAb's 2d-2a can bind with one of their epitopes situated around peptide bond B beta Arg14-Gly15 in dimer fibrinogen molecule reducing the rate of protofibril lateral association and clot turbidity with only one fibrinopeptide B splitting off per fibrinogen molecule by thrombin. But two molecules of Fab-fragments of monAb's 2d-2a join to both of their epitopes and inhibit fibrinogen clotting dramatically without clot formation and with no fibrinopeptide B splitting off. These data suggest that the site of fibrin protofibril lateral coalescence is localized in NH2-terminal part of fibrin (ogen) B beta-chain, i.e. central E-domain of fibrin molecule takes part in protofibril lateral association. The mutual space orientation of NH2-terminal regions of fibrinogen B beta-chains is discussed.