In the dairy industry, enzymes are used to remove lactose from milk as some people are allergic to lactose. The enzyme lactase is added to the milk and hydrolises the lactose to glucose and galactose. Enzymes are also used to assist the extraction of fruit juices from fruits such as oranges and apples. To extract the fruit juices an insoluble pectin is added which causes the plant cell walls to stick to the adjacent cells during storage. This pectin then changes to a soluble form which binds water strongly. Pectinase is then used to break down the pectin chains. This reduces its water-storage capacity so that the fruit can now be crushed and thus release a greater yield of juice.
In the brewing industry the essential product is alcohol which is produced by the action of yeasts on plant materials such as barley, hops and rice. The form of the sugar present in the plant materials is made up of polysaccharides such as starch, which are very complex and so cannot be readily utilised. The yeast cells are only capable of converting simple sugars into alcohol and carbon dioxide. These simple sugars were traditionally released by a process of malting where the barley was allowed to partly germinate so that the endogenous enzymes which were released would degrade the starch and protein into simple sugars and amino acids which could be utilised by the yeast cells. This was an expensive way to manufacture enzymes and today industrial enzymes such as amyloglucosidase are produced much more cheaply and result in the production of the same simple sugars and amino acids that tradition malting would liberate. Other enzymes are also used to improve filtration methods. Xylanases and gluconases break down the viscous polysaccharides of xylan and glucan which used to slow down the filtration of the final beer. This greatly increases the filtration rates.
In the baking industry, proteases are used to lower the protein content of flour during biscuit production. In the leather industry, trypsin is used to help make the leather more pliable by removing hair and excess tissue from the hides and skin. In the agricultural industry ligases are used to make the cellulose in wood waste available for animal feed. And the treatment of starch with enzymes has resulted in a variety of sweet syrups such as glucose, maltose and fructose syrups which are widely used throughout the food and beverage industries.
Enzymes are not only used in industry but are also used in medicine. Enzymes such as trypsin are used to dissolve blood clots and also to clean wounds. Enzymes also take an important role in checking if a patient is diabetic or not. A doctor may use a clinistix which is a strip of cellulose that have the enzyme glucose oxidase on one end of it. When this strip is dipped into the patient’s urine which contains glucose, the reaction produces hydrogen peroxide. This will then react with another compound to give a colour change suggesting that the patient is potentially diabetic.
Enzymes also have many roles in the pharmaceutical industry. Enzymes can be used as direct pharmaceutical products which can be used in the treatment of things such as genetic disorders which are caused by an enzyme deficiency. Enzymes such as restriction endonucleases and DNA polymerases are used in processes such as cloning cells and genetically modifying plants and other organisms and are also used in the field of molecular biology.
ELISAs (Enzyme-linked Immunosorbent assay) are used in hospitals to diagnose certain diseases as specific proteins are detected in blood plasma and other fluids. This technique is also used to detect viruses, bacteria and even pregnancies. It works by selecting the protein which is to be detected, and then antibodies which are known to bind to this protein are fixed to a plate. If the protein is present, it will bind to the antibody and all other proteins will be washed away. A second type of antibody which is linked to an enzyme is added to the protein at a different site to the first protein that was added, a specific substrate is then added which will bind to the active site of this enzyme and the product formed is easily detectable as it will be brightly coloured. The product would not form in the plate at the beginning if the protein was not there.
