An example is the reaction of permanganate ion with oxalic acid to form carbon dioxide and manganous ion, in which the manganous ion acts as an autocatalyst. Such reactions are potentially dangerous, since the reaction rate may increase to the point of explosion. Alumina is a promoter for iron when it is used to catalyze the reaction of hydrogen and nitrogen to form ammonia. Substances that react with catalysts to reduce or eliminate their effect are called poisons. Most of the chemical reactions that occur in the human body and in other living things are high-energy reactions that would occur slowly, if at all, without the catalysis provided by enzymes.
Some enzymes increase reaction rates by a factor of one billion or more.
Usually the enzyme and its substrate have complementary structures and can bond together to form a complex that is more reactive due to the presence of functional groups in the enzyme, which stabilize the transition state of the reaction or lower the activation energy. 7 Laboratory and Industrial Catalysts Catalysis is also important in chemical laboratories and in industry. Some reactions occur faster in the presence of a small amount of an acid or base and are said to be acid catalyzed or base catalyzed. For example, the hydrolysis of esters is catalyzed by the presence of a small amount of base. In this reaction, it is the hydroxide ion, OH - , that reacts with the ester, and the concentration of the hydroxide ion is greatly increased over that of pure water by the presence of the base.