Polymerization properties of two normally circulating fibrinogens, HMW and LMW. Evidence that the COOH-terminal end of the a-chain is of importance for fibrin polymerization.
The plasma fibrinogen fractions HMW (mw 340,000) and LMW (mw 305,000) were prepared from purified (beta-alanine precipitated) fibrinogen by step-wise precipitation with ammonium sulfate. The thrombin clotting times were 14" and 20" respectively. The enzymatic phase of coagulation, measured as release of fibrinopeptide-A during incubation with thrombin, was found to be identical for HMW and LMW. Polymerization was studied by light scattering (at 605 nm) using preformed monomers (des-AA and des-AABB) prepared from HMW and LMW in the presence of 3.3 M urea by incubation with thrombin (100 NIH U/ml final conc.) and reptilase (1 U/ml final conc.). The HMW-monomers polymerised at a substantially higher rate than the corresponding LMW-monomers. Thus, the prolonged clotting time of LMW was explained by retarded polymerization. It is suggested that the -COOH terminal end of the a-chain, containing the molecular difference between HMW and LMW, is of importance for polymerization. Furthermore, the release of fibrinopeptide B (des-AABB-monomers) improved polymerization properties in HMW as well as in LMW, and all types of monomers polymerised more rapidly in the presence of Ca++.
D005337:Fibrin / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D005344:Fibrinopeptide A / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008027:Light; D046911:Macromolecular Substances; D008970:Molecular Weight; D012542:Scattering, Radiation; D013918:Thrombin Time
D046911:Macromolecular Substances; D005344:Fibrinopeptide A; D005337:Fibrin; D005340:Fibrinogen