Natural Coagulation Factors

Prothrombin produced in the liver is a vitamin K-dependent plasma protein. Before prothrombin is secreted into the plasma it goes through post translational modification by vitamin K-dependent carboxylase. The vitamin K-dependent carboxylase convertsprothrombin to 10 glutamic acid residues to gamma carboxyglutamic acid. Prothrombin comprises of 2 kringle regions which are found among residues a.a. 40 & 270 of the mature plasma protein and substitute the growth factor domains located in numerous plasma serine proteases.

Tissue factor is well-known as the main cellular initiator of blood coagulation. The Tissue factor gene encodes coagulation factor III which is a cell surface glycoprotein that enables cells to initiate the blood coagulation cascades, and functions as the high-affinity receptor for the coagulation factor VII. Following vessel injury, the Tissue Factor and Factor VIIa complex activates the coagulation protease cascade, which leads to fibrin deposition and activation of platelets. The ensuing complex presents a catalytic event, which is responsible for initiation of the coagulation protease cascades by specific limited proteolysis. Therefore, Tissue factor has a role in normal hemostasis by initiating the cell-surface assembly and propagation of the coagulation protease cascade. Tissue Factor can also be stimulated by the inflammatory mediators interleukin 1 and TNF, as well as by endotoxin, to appear on monocytes and vascular endothelial cells as a component of cellular immune response.
Tissue factor is the only one in the coagulation pathway for which a congenital deficiency has not been described. Certain levels of Tissue Factor are essential for the maintained viability and growth of endothelium and Tissue Factor-expressing tumor cells. Additionally, abnormal Tissue Factor expression inside the vasculature initiates life threatening thrombosis in various diseases, for example sepsis, atherosclerosis, and cancer. Alternative spliced Tissue Factor expression advances tumor growth, and is linked to increased tumor cell proliferation and angiogenesis in pancreatic cancer.

Prothrombin Complex Concentrate (PCC) is a combination of several blood clotting factors II, VII, IX and X. PCC is used in the treatment of the congenital bleeding disorders associated with Factors II, VII, IX, and X deficiencies. PCC reverses the effect of warfarin (a coumarin anti-coagulant) and is used in cases of significant bleeding in patients with a coagulopathy, for example, gastrointestinal haemorrhage or intracranial haemorrhage. The PCC is also extensively used in treating acquired coagulation abnormalities secondary to vitamin K deficiency, warfarin ingestion, and various types of liver disease.
Hepatitis, anaphylaxis and thrombosis have been reported as complications of prothrombin complex concentrates administration.

Human Factor IX also called Christmas-Factor is a glycoprotein, which is synthesized in the liver and belongs to the serine proteases system and is part of the S1 peptidase family.
Lack of Factor-IX causes Hemophilia-B meaning Christmas Disease. Factor-IX has a N-terminus region which contains 12xGla residues which asist the calcium dpendant binding of Factor-IX to the phospholipid surface. Factor-IX is activated by either factor XIa or the factor VIIa/tissue factor/phospholipid complex. Cleavage yields the intermediate IXa, which is subsequently converted to the fully active form IXab.
Factor-IX binds initially to exosites on the factor XIa heavy chain, followed by interaction at the active site with subsequent bond cleavage. Coagulation factor IX is activated by interaction with the erythrocyte membrane, causing intrinsic coagulation. Chaperones & lectins act simultaniously to guarantee the proper folding of Factor-IX and the retention of mutant molecules. Human Factor IX, activated by either the Contact or Tissue Factor Pathway, is responsible for the activation of Factor X to Xa.