Fibrin

Fibrin (also called Factor Ia) is a fibrous, non-globular protein involved in the clotting of blood. It is a fibrillar protein that is polymerised to form a "mesh" that forms a hemostatic plug or clot (in conjunction with platelets) over a wound site.

Fibrin is involved in signal transduction, blood coagulation, platelet activation, and protein polymerization.

Role in disease
Excessive generation of fibrin due to activation of the coagulation cascade leads to thrombosis, more commonly known as a clot, while ineffective generation or premature lysis of fibrin predisposes to hemorrhage.

Dysfunction or disease of the liver can lead to a decrease in fibrinogen production or the production of abnormal fibrinogen molecules with reduced activity (dysfibrinogenaemia). Hereditary abnormalities of fibrinogen (the gene is carried on chromosome 4) are of both quantitative and qualitative in nature and include; afibrinogenaemia, hypofibrinogenaemia, dysfibrinogenaemia, and hypodysfibrinogenaemia.

Consequences of reduced, absent, or dysfunctional fibrin is likely to render patients as hemophiliacs.

Physiology
Fibrin from different animal sources is generally glycosylated with complex type diantennary asparagine linked glycans. Variety is just found in the degree of core fucosylation and in the type of sialic acid and galactose linkage.

Structure


The image at the left is a crystal structure of the double-d fragment from human fibrin with two bound ligands. The experimental method used to obtain the image was X-ray diffraction, and it has a resolution of 2.30 Å. The structure is mainly made up of single alpha helices shown in red and beta sheets shown in yellow. The two blue structures are the bound ligands. The chemical structures of the ligands are Ca+2 ion, alpha-D-mannose (C6H12O6), and D-glucosamine (C8H15NO6).