Enzyme

enzyme.

     An organic protein substance produced by living cells and that acts as a catalyst in biological and biochemical changes such as synthesis, hydrolysis, oxidative degradation, and isomerization. Enzymes are highly specific and act on only one substrate and affect only one type of chemical reaction. Alpha-amylase, for example, converts starch to maltotriose and dextrins whereas beta-amylase converts dextrins to maltose, maltotriose, and alpha-limit dextrins. Enzymes are sensitive to heat and undergo denaturation at high temperatures and have a low tolerance to a pH of 4 or less.