Some aspects of the bonds interlinking soluble fibrin complexes in human plasma

I¹²⁵ labelled fibrinogen was used to study the appearance of soluble fibrin complexes in thrombin incubated citrated plasma or in glass activated native plasma. Polyacrylamide gel (4%) electrophoresis demonstrated that approximately 7% of the plasma fibrinogen had been converted to slower moving species, eg. soluble fibrin complexes. Only a minor part of these complexes, with mobility as a fibrinogen derived dimer, persisted upon electrophoresis in the presence of 5 M urea. Also, agarose gel chromatography (Seph. 4 B) revealed the formation of high molecular weight fibrin/fibrinogen derivatives, which disappeared when chromatography was performed in the presence of 5 M urea.Thus, the major part of the soluble fibrin complexes in plasma was not resistant to urea, indicating that mainly non covalent bonds were involved. This implicates only a minor part of such complexes in a plasma milieu to be cross-linked through the action of the Fibrin Stabilizing Factor.