Zymogen

Zymogens ( proenzymes or ) are inactive enzyme precursors. Examples are pepsinogen or chymotrypsinogen. In contrast to it apoenzymes by proteases ( proteolysis ) or the enzyme itself ( autoproteolysis ) are converted to the active form. The difference to apoenzymes is that in this post-translational modification, covalent bonds are broken. Zymogens are a special case of a precursor protein.

Zymogens are important in the processes of digestion, since the enzyme if it was already active during transportation to the actual site of action could possibly attack other enzymes or structural proteins of the body.

An example of a condition caused by premature activation of digestive enzymes is the pancreatitis ( inflammation of the pancreas ), in which due to a blockage of the bile duct, the enzymes made ​​by the pancreas are activated before the digestive tract, and damage to the pancreas or the surrounding tissue.

Are of particular importance as zymogens further coagulation factors, precursors of the active coagulation enzymes that intervene in cascade in the blood clotting system. Moreover, it is the process of zymogen activation in the immune response in a number of factors of the complement system.