[The effect of fragment D on the aggregation of fibrinogen molecules in solution]

The mechanism of fibrinogen aggregation in the presence of fragment D has been studied. The values of translational diffusion coefficients, specific viscosity, average molecular masses, and Zimm factor of light scattering indicate that fragment D accelerated assembly of fibrinogen molecules that form flexible polymeric chains with tail-to-tail association due to spontaneous structural modification of COOH-terminal regions. Electrophoresis did not reveal the presence of fragment D in polymer fraction of non-reduced samples. The data obtained allowed to conclude that at initial stages fragment D forms unstable complexes with structurally modified fibrinogen molecules. These complexes serve as intermediates in the multistep process of assembly of supermolecular protein complex.