An integrated study of fibrinogen during blood coagulation.
The rate of conversion of fibrinogen (Fg) to the insoluble product fibrin (Fn) is a key factor in hemostasis. We have developed methods to quantitate fibrinopeptides (FPs) and soluble and insoluble Fg/Fn products during the tissue factor induced clotting of whole blood. Significant FPA generation (>50%) occurs prior to visible clotting (4 +/- 0.2 min) coincident with factor XIII activation. At this time Fg is mostly in solution along with high molecular weight cross-linked products. Cross-linking of gamma-chains is virtually complete (5 min) prior to the release of FPB, a process that does not occur until after clot formation. FPB is detected still attached to the beta-chain throughout the time course demonstrating release of only low levels of FPB from the clot. After release of FPB a carboxypeptidase-B-like enzyme removes the carboxyl-terminal arginine resulting exclusively in des-Arg FPB by the 20-min time point. This process is inhibited by epsilon-aminocaproic acid. These results demonstrate that transglutaminase and carboxypeptidase enzymes are activated simultaneously with Fn formation. The initial clot is a composite of Fn I and Fg already displaying gamma-gamma cross-linking prior to the formation of Fn II with Bbeta-chain remaining mostly intact followed by the selective degradation of FPB to des-Arg FPB.
Brummel
K E
KE
Department of Biochemistry, Given Building, Health Science Complex, University of Vermont, College of Medicine, Burlington, Vermont 05405-0068, USA.
Butenas
S
S
Mann
K G
KG
D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D015119:Aminocaproic Acid / Q000494:pharmacology; D001777:Blood Coagulation / Q000502:physiology*; D043424:Carboxypeptidase B; D002268:Carboxypeptidases / Q000378:metabolism; D004789:Enzyme Activation; D005176:Factor XIII / Q000378:metabolism; D005337:Fibrin / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D005344:Fibrinopeptide A / Q000378:metabolism*; D005345:Fibrinopeptide B / Q000378:metabolism*; D006467:Hemophilia A / Q000378:metabolism; D006801:Humans; D008954:Models, Biological; D008969:Molecular Sequence Data; D011480:Protease Inhibitors / Q000494:pharmacology; D011487:Protein Conformation; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013925:Thromboplastin / Q000494:pharmacology; D011503:Transglutaminases / Q000378:metabolism
D011480:Protease Inhibitors; D005344:Fibrinopeptide A; D005345:Fibrinopeptide B; D005337:Fibrin; D005340:Fibrinogen; D005176:Factor XIII; D013925:Thromboplastin; D011503:Transglutaminases; D002268:Carboxypeptidases; D043424:Carboxypeptidase B; D015119:Aminocaproic Acid