Fibrin

Fibrin (also called Factor Ia) is a fibrous, non-globular protein involved in the clotting of blood. It is formed by the action of the protease thrombin on fibrinogen, which causes it to polymerize. The polymerized fibrin, together with platelets, forms a hemostatic plug or clot over a wound site.

When the lining of a blood vessel is broken, platelets are attracted, forming a platelet plug. These platelets have thrombin receptors on their surfaces that bind serum thrombin molecules,^[1] which in turn convert soluble fibrinogen in the serum into fibrin at the wound site. Fibrin forms long strands of tough insoluble protein that are bound to the platelets. Factor XIII completes the cross-linking of fibrin so that it hardens and contracts. The cross-linked fibrin forms a mesh atop the platelet plug that completes the clot. Fibrin was discovered^[2] by Marcello Malpighi in 1666.^[3]

Role in disease

Excessive generation of fibrin due to activation of the

Dysfunction or disease of the liver can lead to a decrease in the production of fibrin's inactive precursor,

Reduced, absent, or dysfunctional fibrin is likely to render patients as hemophiliacs.

Physiology

Fibrin from various different animal sources is generally

Fibrin is formed after thrombin cleavage of fibrinopeptide A (FPA) from fibrinogen Aalpha-chains, thus initiating fibrin polymerization. Double-stranded fibrils form through end-to-middle domain (D:E) associations, and concomitant lateral fibril associations and branching create a clot network.

• D-dimer
• Fibrin glue
• Fibrin scaffold
• Fibrinolysis

References