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Enzyme Explorer

Fibrinogen & Fibrin

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Physical Properties

Fibrinogen is synthesized in the liver and is circulated in plasma at ~200-450 mg/dL. It is a dimeric glycoprotein composed of three pairs of peptide chains. The two subunits are composed of a D domain which contains a globular region and an E domain which contains a disulfide bond that links the two subunits.

Molecular Mass:

Soluble Dimer: 340 kDa
α chain: 63.5 kDa
β chain: 56 kDa
γ chain: 47 kDa
E1% = 15.1
PI ≈ 5.5
Fibrinogen sequence


Fibrinogen is an acute phase protein that is part of the coagulation cascade of proteins. The end result of the cascade is the production of thrombin that converts fibrinogen to fibrin.

Fibrinogen cascade

Thrombin rapidly proteolyzes fibrinogen, releasing fibrinopeptide A. The loss of this small peptide is not sufficient to make the resulting fibrin molecule insoluble, but it tends to form complexes with adjacent fibrin and fibrinogen molecules. Thrombin then cleaves a second peptide, fibrinopeptide B, from fibrin and the fibrin monomers formed then polymerize spontaneously to form an insoluble gel. The polymerized fibrin is held together by noncovalent and electrostatic forces and stabilized by the transamidating enzyme, factor XIIIa, that is produced by the action of thrombin on factor XIII. The insoluble fibrin aggregates (clots) and aggregated platelets then block the damaged blood vessel and prevent further bleeding. The amount of fibrinogen in the plasma can serve as a nonspecific indicator of whether or not an inflammatory process is present in the body. Fibrinogen from any mammalian source will be cleaved by thrombin from any mammalian source.1

Fibrinogen and fibrin cleavage points

Hydrolysis of polymerized fibrin occurs when plasminogen is activated in the proximity of fibrin. Plasmin cleaves fibrin in the coiled region between the D and E domains as well as cleaving a peptide from the C-terminal region of the α-chain.

Degraded Fibrin


Product Product #
Fibrin from human plasma F5386
Fibrinogen from bovine plasma Type IV F4753
Fibrinogen from bovine plasma Type I-S powder F8630
Fibrinogen from cat plasma F8513
Fibrinogen from canine plasma F7128
Fibrinogen from human plasma Type I F3879
Fibrinogen from human plasma Type III F4129
Fibrinogen from human plasma, Essentially plasmin(ogen) free powder F4883
Fibrinogen from murine plasma F4385
Fibrinogen from porcine plasma F2629
Fibrinogen from rat plasma F6755
Fibrinogen from sheep plasma F9754
N-Acetyl-Pen-Arg-Gly-Asp-Cys [Disulfide bridge: 1-5] ≥97% (HPLC) A5582
Related Peptides  
Gly-Pro-Arg-Pro ≥97% (HPLC G1895
Gly-Pro-Arg-Pro amide ≥97% (HPLC) G5779
Fibrinogen-binding Inhibitor Peptide ≥97% (HPLC) F9145
Fibrinopeptide A ≥97% (HPLC) F3254
Fibrinopeptide B Human ≥97% (HPLC) F3379
[Glu1]-Fibrinopeptide B human ≥90% (HPLC) F3261


The Plasma Proteins, 2nd ed., 2, Putnam, F. W., ed, p. 148.

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