Applications of enzyme chemistry

• Enzymes are sometimes enhanced and supported in their activity by smaller molecules or metals ions. These reactants are called co-enzymes. We will not look further into the mechanisms of co-enzymes.
• Enzymes are not only used in our bodies to speed up reactions; they are also commercially used. One such case is ‘enzyme’-enriched detergents, which ‘eat away the dirt’.
• There are many other clever applications of enzymes in the chemical industry. For example, the soft centres of some hard boiled sweets contain a minute quantity of an enzyme. It slowly reacts to soften the sweet from the centre outwards and so causes the centre of the sweet to be soft and chewy.
  
• Enzymes in yeast help ferment sugars to make alcohol (ethanol).  Enzymes can be poisoned if an impurity molecule blocks up the active site of the enzyme. Some enzymes can be used in treatments to prevent unwanted reactions occurring, like the production of bacteria.
• Some diseases are caused by enzyme deficiencies. The congenital disease phenylketonuria is caused by the deficiency of the enzyme phenylalanine hydroxylase, resulting in a build-up of compounds that cause brain damage and mental retardation. This damage can be lessened and prevented by a diet containing a low amount of the amino acid phenylalanine. The complaint is caused by a genetic mutation.
• Albinism is also caused by lack of the enzyme tyrosinase, resulting from a genetic defect.
• Many heart attacks are caused by a blood clot forming in a coronary artery, and recently this has been found to respond to the enzyme streptokinase to dissolve the clot. It is injected to as close to the clot as possible.
• When blood is required to clot, as in the case of a cut or wound, enzymes are involved. Thrombin catalyses t the soluble protein, fibrin, in the blood to form the insoluble fibrin, helping clotting and wound repair.
• Amylase in the saliva and small intestine helps convert starch to maltose, and this in turn is converted into glucose in the small intestine with the enzyme maltase present. Glucose is either used for energy release or stored as glycogen for future use.
• Gastric enzymes such as pepsin and trypsin convert proteins from food into the smaller peptide molecules, which in turn are converted into amino acids.
• In the small intestine there is lipase, which converts fats (or lipids) into fatty acids.
• The disaccharide lactose, is only found in milk and is hydrolysed with water in the presence of an enzyme lactase to form the monosaccharide glucose and galactose. This occurs in the small intestine. Some people, and particularly those from Eastern and African countries, are deficient in lactase so they are intolerant of milk. This can cause diarrhoea. Many African and Chinese foods do not include milk for this reason.
• Antabuse, or disulfiran, is used to deter alcoholics from drinking alcohol again. They take the drug, and then when they consume alcohol they feel sick and nauseous. This is because the antabuse inhibits the enzyme that aids the oxidation of ethanal, an aldehyde which is one of the products of alcohol oxidation in the system. The build-up of ethanal makes the person feel sick. The effect slowly wears off but leaves a memory of nausea.5
• It has been known for a long time that the presence of too high a concentration of free radicals can have a damaging effect on the DNA of a cell by its electrons being stolen by the free radical. However, it has only recently been realized that all organisms have enzymes that can repair any damage caused by this process. Exactly how the enzyme travels along the long DNA chains to find the damaged parts and repair them is a mystery waiting to be unravelled.