Yatsenko T. Molecular mechanisms of fibrinolysis regulation by fibrinogen/fibrin fragments

Object: fibrinolytic system proteins, fibrinogen/fibrin and their degradation products. Aim: investigation of fibrinogen/fibrin fragments role in the molecular mechanisms of fibrinolytic process regulation and initiation. Methods: preparative biochemistry methods, physical and chemical (spectrophotometry, turbidimetry, electrophoresis), chromatography (size-exclusion, ion-change and affinity chromatography), immunochemical (enzyme-linked immunoassay, western-blot) methods, enzymes activity evaluation by chromogenic substrate. It was demonstrated that fibrinogen/fibrin fragments can regulate different stages of the fibrinolytic process and slow clot lysis rate. Fragment Ee, as well as E1,E2 mixture, demonstrates high stimulation ability, what indicates of plasminogen- and tissue-type activator-binding sites in the fragments. The results confer the requirement of fibrinogen/fibrin D-domains structural changes, related to ?- and ?-subdomains calcium-binding sites reorganization and ?-chains covalent cross-linking during fibrin polymerization, for the fibrinolytic process initiation. The result of investigation of plasminogen and its fragments interactions with D-domain containing fibrinogen/fibrin fragments indicates localization of binding sites for plasminogen fragments K 1-3 and K 5 in D-domain wich can be located in ?-, ?- and ??-chains. Using obtained data, we have developed new quantitative method for the evaluation of tissue-type activator activity in blood plasma samples.