Fibrinogen (Coagulation Factor I)

Fibrinogen (clotting factor I) is a heat labile beta glycoprotein (molecular weight 340000) and consists of three pairs of chains bound by disulphide bonds. It is synthesized in hepatocytes under genetic control. It is the precursor of fibrin, which is the key protein constituting the network of the blood clot. Thrombin converts fibrinogen to fibrin by limited proteolysis, releasing the fibrinopeptides A and B (molecular weight 50000-65000) and forming fibrin monomers. Fibrin monomers polymerize to fibrin which is stabilized by cross-linking under the influence of factor XIII. The predominant gamma chain of normal fibrinogen (MW 50000, with higher variants) has a low affinity for platelet binding. The normal concentration of fibrinogen in the blood is 2.5-3.5ml/ml, but lower levels are usually adequate for haemostasis. In newborn infants the value is 1.2-2.4mg/ml. Synthesis of fetal fibrinogen may persists for up to 8 weeks, when adult levels are reached. Adult level increase with age and are a risk for heart disease, myocardial infarction and stroke. Fibrinogen is an acute Phase protein and increased levels are found in loosing enteropathies, in severe malnutrition, in tissue necrosis and in malignancy. Extremely high levels are seen in acute pancreatitis and, to a lower extent, in nephritic syndrome. A moderate raise may also been seen during pregnancy and the use of oral contraceptives. Fibrinogen deficiency may be congenital or acquired. If sufficiently severe, it may result in a bleeding disorder. The congenital form is very rare. Acquired hypofibrinogaemia is relatively common, probably indicating increased consumption during intravascular clotting. Applications: Suitable for use in ELISA, Immunoelectrophoresis and Radial Immunodiffusion. Other applications not tested. Recommended Dilution: Optimal dilutions to be determined by the researcher. Storage and Stability: Lyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with sterile ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Reconstituted product is stable for 12 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.