An enzyme is a protein produced by the body to speed up a specific chemical reaction in the body. The body produces many different kinds of enzymes for many different body processes, such as digestion and blood clotting.
Some inherited diseases are caused by problems with the production of certain enzymes. Doctors may measure the levels of certain enzymes in a person's blood to help diagnose certain types of disease, such as liver problems.
WebMD Medical Reference from Healthwise