What are enzymes?

            The human body is a machine that needs energy to work. This energy is obtained from food materials through metabolism. These metabolic processes are carried on by activating agents or catalysts called enzymes. Let us see what enzymes are and what they do in our body.

             An enzyme is an organic catalyst produced by a living cell. All enzymes are proteins made up of long chains of amino acids. They combine with the substrate to form an intermediate compound. This intermediate compound is an unstable complex, and breaks down to yield the reaction product, plus the original enzyme.

             Enzymes are themselves synthesized by other enzymes derived from nucleic acids. An average cell contains about 3000 different enzymes. In order to function correctly, many enzymes require the assistance of related substances known as co-enzymes which are produced from vitamins in the diet.

             The human body literally contains hundreds of different enzymes. Many are contained within the cells, but some others, such as those used for digestive purposes, act outside cells in the gut itself. Enzymes are involved in almost every chemical reaction taking place in our body.

             Many physiological activities such as digestion, building up and breaking down of tissues, cellular respiration and muscle contraction depend on their action. The activity of an enzyme depends on the temperature, the degree of acidity or alkalinity (pH) and the substance upon which the enzyme acts. A single enzyme molecule is capable of bringing about the required changes on hundreds of molecules of the substrate in a few seconds.

             Enzyme action can be blocked by some poisonous substances such as mercury, lead or arsenic. The presence of such substances hinders the enzymes from forming intermediate complex with the substrate. Normal metabolism is thus prevented.

            Enzymes are classified into six major groups: Oxidases which bring about oxidation, transferases which bring about group transfer; hydrolases which speed up the process of hydrolysis; lyases that bring about group removal. Isomerases enzymes are responsible for isomerization and ligases for joining of molecules.

           Enzymes are not only important for our body, but are also very useful in industry, medicine and analytical chemistry. Although enzymes normally work inside living cells still they are capable of working outside the cell. They are used to convert starch into glucose and glucose into fructose. They are also used in cheese-making industry and for the production of semi-synthetic penicillin. Artificial sweeteners are also produced with their help.