Fibrin is a fibrous, non-globular protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 involved in the clotting of blood. It is a fibrillar protein that is polymerised
In polymer chemistry, polymerization is a process of reacting monomer molecules together in a chemical reaction to form three-dimensional networks or polymer chains...

 to form a "mesh" that forms a hemostatic
Hemostasis or haemostasis is a process which causes bleeding to stop, meaning to keep blood within a damaged blood vessel . Most of the time this includes blood changing from a liquid to a solid state. Intact blood vessels are central to moderating blood's tendency to clot...

 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
Thrombosis is the formation of a blood clot inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot to prevent blood loss...

, the block of a vessel by an agglutination of red blood cells, platelets, polymerized fibrin and other components. Ineffective generation or premature lysis
Lysis refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate"....

 of fibrin predisposes to hemorrhage.

Dysfunction or disease of the liver can lead to a decrease in the production of fibrin's inactive precursor, fibrinogen
Fibrinogen is a soluble plasma glycoprotein, synthesised by the liver, that is converted by thrombin into fibrin during blood coagulation. This is achieved through processes in the coagulation cascade that activate the zymogen prothrombin to the serine protease thrombin, which is responsible for...

, or to 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.


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
Fucosylation : The process of adding fucose sugar units to a molecule. It is a type of Glycosylation.It is important clinically, especially in cancer.It is performed by fucosyltransferase enzymes....

 and in the type of sialic acid
Sialic acid
Sialic acid is a generic term for the N- or O-substituted derivatives of neuraminic acid, a monosaccharide with a nine-carbon backbone. It is also the name for the most common member of this group, N-acetylneuraminic acid...

 and galactose
Galactose , sometimes abbreviated Gal, is a type of sugar that is less sweet than glucose. It is a C-4 epimer of glucose....



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).

External links

  •, Defibrinated blood harvested from sheep (video)
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