enzyme

any PROTEIN molecule that acts as a catalyst in the biochemical processes of the body. They are essential to life and are highly specific, acting on certain substrates at a set temperature and pH. Examples are the digestive enzymes amylase, lipase and TRYPSIN . Enzymes act by providing active sites (one or more for each enzyme) to which substrate molecules bind, forming a short-lived intermediate. The rate of reaction is increased, and after the product is formed, the active site is freed. Enzymes are easily rendered inactive by heat and some chemicals. They are vital for the normal functioning of the body, and their lack or inactivity can produce metabolic disorders.