Subunit and macromolecular structure of circulating fibrin from obstetric patients with intravascular coagulation

Abstract

Circulating crosslinked fibrin was observed in 19 patients with coagulation disorders in obstetrics (amniotic fluid embolism, abruptio placentae, endotoxin shock following septic abortion etc.). Gel filtration of B-Alaprecipitated plasma samples and chain characterization of isolated fibrin derivatives by SDS-PAA gel electrophoresis after reduction with mercaptoethanol were performed. Fibrin was observed in amounts up to 30 mg/100 ml plasma. Subunit structure analysis revealed that circulating fibrin is composed of γ-γ-γ-γ′ (85 000 molecular weight), β, (β′) (52 000 mol. wt.), γ, β″ (44 500 mol. wt.), α (25 000 mol. wt.) and α ″ (15 000 mol. wt.) chains. This composition reflects the action of thrombin, factor XIII and plasmin and agrees with the assumption of γ chain crosslinked late-X oligomers (intermediate polymers). Their mean molecular weight is 1–2 million daltons. Electron microscopy of fibrin following freeze etching technique shows that di-, tri- and higher-ordered oligomers are arranged in an end-to-end association. In vitro produced partially crosslinked oligomers of late-X fragments exhibited a very similar subunit and macromolecular structure.