A protein that regulates the rate of a chemical reaction in the body. There are thousands of enzymes, each with a different chemical structure. It is this structure that determines the specific reaction regulated by an enzyme. Different enzymes occur in different tissues, reflecting their specialized functions. In order to function properly, many enzymes need an additional component, known as a coenzyme, which is often derived from a vitamin or mineral. Enzyme activity is influenced by many factors, and can be increased or inhibited by certain drugs. Measuring enzyme levels in the blood can be useful in diagnosing certain disorders. For example, the level of heart muscle enzymes is raised following a myocardial infarction because the damaged heart muscle releases enzymes into the bloodstream. Many different inherited metabolic disorders, including phenylketonuria, galactosaemia, and G6PD deficiency, are caused by defects in, or deficiencies of, specific enzymes. Enzymes can play a valuable role in treating certain disorders. Pancreatic enzymes may be given as digestive aids to people who have malabsorption related to pancreatic disease. Enzymes such as streptokinase and tissue-plasminogen activator are used to treat acute thrombosis and embolism.


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