[Biologically active low-molecular fragments of fibrinogen molecule]

A peptide fraction with a specific property of interaction with D fragment was found in the fibrinogen tryptic hydrolyzate. This fraction is called a protector. In the protector presence the time of the monomer fibrin polymerization prolonged with D fragment is greatly lowered. The protector was found in the first minutes of fibrinogen degradation. It was shown for low concentration of trypsin (enzyme-substrate ratio being 1:7500). The gel filtration of a tryptic fibrinogen hydrolyzate on Sephadexes G-10, G-15, G-25 showed that the protector has a low molecular weight. It was found that a preincubation of the protector with D fragment should take place before interaction of their mixture with a fibrin monomer. The interaction of the protector with D fragment is reversible.