CNBr Fibrinogen fragments
Fibrinogen is the main plasma coagulation factor. It exhibits a molecular weight of 340KD and consist of a dimer of A-alpha-, B-beta– and gamma-chains, held together by disulfide bridges. Upon thrombin cleavage of the A-alpha– and B-beta-chain, fibrinopeptide A and thereafter fibrinopeptide B moieties are released. Binding sites from C-terminal regions of other fibrinogen or fibrin molecules are generated in the new aminoterminal. This allows formation of fibrin polymers which can be crosslinked by fibrin stabilizing factor. Fibrin is highly susceptible to proteolysis by plasmin which initially leaves the C-terminal part of the alpha-chain generating lysine residues shich, in turn, are involved in the binding of kringle structures leading to maximal stimulation of plasminogen activation by tissue plasminogen activator.
The stimulating effect of fibrin on plasminogen activation by t-PA is also mimicked my cyanogen bromide (CNBr) fragments of fibrinogen. Technoclone CNBr-fragments of fibrinogen are obtained by cyanogen bromide digestion of purified human fibrinogen according to the method of Blombäck et al. N-terminal disulphide knot of human fibrinogen. Nature 218: 130-134, 1968