Fibrin

Fibrin (Latin fibra, fiber ') is activated, networked "glue" of the plasmatic clotting. Is a protein that is formed by the action of the enzyme thrombin, from the thread-like soluble precursor fibrinogen. Then, the fibrin polymerizes and forms a network, the blood clot ( " white thrombus ") which closes the wound. Only later will the soft thrombus to form a hard crust by cross-linking using the factor XIIIa. Fibrin may accelerate in the presence of pure oxygen or specific oxidative wound irrigation wound healing.

Details of fibrin

In the formation of the white thrombus which is 16 amino acids long first cleaved fibrinopeptide A and the β - chain of the 14 amino acids long fibrinopeptide B by thrombin of the α - chain of fibrinogen. Thus, the N -terminal position is exposed to the peptides and commit them to the γ - chain of fibrinogen and settle there to so-called protofibrils together. In the next step, enter protofibrils to more or less thick fibrin fibers in a process together, which is called Lateralassoziation. It also leads to branching, so that a three-dimensional structure is formed.

Pathology of fibrin

The genes FGA, FGB and FGG, coding for the sub-chains of fibrinogen, may have different mutations that can affect the formation of fibrinogen and thus the fibrinopeptides. So hypofibrinogenemias (reduced fibrinogen content of the blood) and Dysfibrinogenämien (abnormal fibrinogen molecules ) are afibrinogenemias (no fibrinogen), is known.

Structural changes in the fibrinogen may have different defects in clot formation leading to:

  • Disturbance of the release of the fibrinopeptides;
  • Altered aggregation of the monomers;
  • Modified Lateralassoziation of protofibrils;
  • Disorder of the later networking.

About 60 percent of the defects are asymptomatic. The symptoms bleeding tendencies dominate, in 15 per cent there is a tendency to thrombosis. Worth mentioning is a group of defects with storage of protein aggregates in kidney and spleen (renal amyloidosis ), where the renal dysfunction dominates the picture.

Blood plasma Hemostasis Digital Object Identifier
333462
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