Blood vessels at times undergo physical stress due to injury such as being cut or damaged, which consequently leads to the loss of blood. This harm can be very dangerous especially when it places the body not to work at its optimum.
To prevent excessive loss of blood, which causes shock and in some scenarios, death, the body has a system of solidifying the blood known as coagulation. This process can only be initiated and carried out by a proteolytic enzyme commonly known as thrombin.
The body naturally produces this protein from its precursor prothrombin, through a cleavage process.
What is Thrombin?
Thrombin belongs to a class of enzymes known as serine proteases. This indicates that thrombin specifically targets the serine moiety of proteins, initiating the coagulation cascade.
The lack of thrombin can cause serious health problems and most people who have a defective blood clotting system makes use of synthesized form of thrombin drugs. They are normally administered under strict doctor’s instructions.
1. Specific Digestion
Thrombin, as stated earlier belongs to the serine proteases class of enzymes. In this class are common gastrointestinal enzymes like trypsin and chymotrypsin.
Thrombin slightly differs from these enzymes since its action is restricted or specific to certain moieties. This means that, thrombin is only responsible for the cleavage that activates fibrinogen.
The specific cleavage with thrombin is made without digesting other important proteins in the blood.
2. Thrombin as the focal point of blood coagulation
In the normal setting, there are specific protein tissue factors that are found on cell surfaces which never come in contact with the blood.
When the blood vessel is cut, the tissue factors come in contact with the blood and initiate a cascade of events, which keep on amplifying until the right response is obtained.
The tissue factors activate some molecules of factor VII, which activates factor X. Thrombin is shortly activated by factor X. It is responsible for converting the signals relayed by the tissue factors into actions.
3. Thrombin’s precision
Thrombin, under normal circumstances will be at the right place, at the right time. This will ensure that the problem in hand is well taken care of without destroying other things in the process.
When thrombin is mistimed or at the wrong place, it will cause unnecessary blood clots that can have catastrophic effects. This can lead to embolisms, strokes, and other blood clot related diseases that can be life-threatening.
4. Thrombin regulation
Thrombin is usually synthesized in an inactive form. The inactive form is normally characterized by several extra domains as compared to the active thrombin.
The extra domains are normally cleaved during the activation process. Thrombin has ions on its surface that have a strong positive charge, which are essential for anchoring the thrombin on the blood vessels and making it immobile.
Once blood clots start, they cannot go far since thrombin has restricted movement. The other way in which thrombin is regulated is by limiting the time it remains active.
Thrombin only lasts seconds after its activation, which consequently leads to the restriction of the clot to the damaged area.
Blood clots are normally important when a blood vessel is damaged, but it is not always needed. This is the reason as to why doctors prescribe certain anticoagulants, which will reverse or inhibit the actions of thrombin.
Drugs like aspirin and warfarin reverse the coagulating effect of thrombin. Leeches naturally produce anticoagulant proteins like hirudin, which inhibit thrombin from forming blood clots.
6. Thrombin’s key roles
Fibrinogen is normally soluble and it is the reason as to why it is important to have it converted into fibrin, which is insoluble. This is a vital key for the formation of the hemostatic plug.
Thrombin is also a key activator of platelets, factor V, and factor VIII. It is also responsible for the inhibition of the protein C.
7. Thrombin and certain diseases
Thrombin is an important part of the blood clotting system, but it has been linked with various diseases.
Certain rare diseases like hypoprothrombinemia, are associated with prothrombin, the inactive form of thrombin. Vasospasm is also linked with thrombin, due to its vasoconstricting properties.
Thrombin also plays a role in the progression or onset of atherosclerosis which is because of the inflammatory effect that it possesses.
8. The blood clotting system and immune system
Thrombin and the entire blood coagulation system are well known for their role in stopping bleeding by the formation of blood clots.
However, the system is not confined to the formation of blood clots. The immune system and the blood clotting system actually overlap.
During the formation of blood clots, there are fibrins, which form a mesh that at times trap different microorganisms in the blood clots.
In addition, some of the elements found in the blood coagulating system act in tandem with the innate immune system. These elements work as chemotactic agents, which work hand in hand with the phagocytes in killing the microbes.
9. Lack of thrombin
The lack of thrombin can cause certain diseases in the body. Vitamin K is essential in the formation of thrombin and its deficiency can cause serious bleeding disorders.
There are certain bleeding disorders that are hereditary like the Von Willebrand disease, characterized by the deficiency of VWF. Liver failure is also a contributing factor that can cause a deficiency in thrombin.
10. Thrombin’s applications
Thrombin can be used outside the body exploiting its serine cleaving properties. As a biochemical tool, it is used to fuse proteins.
It can also be used in the food industry to bind different types of meat together. The coagulating properties enable meat manufacturers to blend different types of meat like fish and beef to form a new meat mixture.
In the medical field, it can be used during surgery where there is blood loss and if it is not handled carefully it can lead to hemorrhage. It’s been useful in many other important functions in the field of science.
Topical administration of aqueous thrombin helps in hemostasis. Therefore, it is also essential in maintaining normal balance and flow of nutrients and oxygen in the body.
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