Kinetic study on the initial stage of the fibrinogen-fibrin conversion by thrombin (I) application of mathematical treatment to turbidimetrical method

Kinetics on the initial reaction of the fibrinogen-fibrin conversion catalyzed by thrombin was studied by turbidimetrical measurement. The turbidity change caused by the conversion reaction was analyzed by a mathematical treatment, assuming that the dimer formation of fibrin monomers was the rate-determining reaction in the stage of polymerization. The obtained relations were investigated under experimental conditions at neutral pH and at low ionic strength, in which fast polymerization rate of fibrin monomers can be expected in comparison with the rate of enzyme reaction. The experimental results analyzed from turbidity-time curves were generally in agreement with theoretical prediction. On the other hand, the plots relating to the enzyme concentration did not lead to anticipated linear relationship. Hence, it was concluded that every fibrin monomer did not always polymerize via dimer formation, but that dimers of fibrin monomers behaved as nuclei for polymerization.