Enzymes in Technology

Many biochemical reactions are used in industry. They give us beer, bread, cheese, yoghurt and many, many other everyday products as well as foods. The major role of enzymes is to speed up reactions and allow them to take place in more reasonable conditions. Hydrogen peroxide, for example, will eventually decompose if left alone; the speed of this breakdown is greatly increased though by the addition of liver tissue.

The reactions used in industry are much more complex. The production of beer, for example, is a very complex process utilising enzymes in yeast that convert sugars to alcohol. In warmer climates, people leave fruit juices out in the sun allowing the sugars to ferment to make the same product. Bread production requires yeast to undergo respiration too. The alcohol produced is evaporated off though.

To feed our appetite for sweet sugars, the fructose we eat comes not from honey but from hydrolysed corn starch. This finds its way to becoming glucose which is isomerised (by an enzyme) to sweet fructose.

Enzymes are catalysts. They speed up reactions by allowing them to take place without solely the need for direct collisions between reactants. Enzymes normally allow the reaction to take place at a lower temperature as the activation energy for the reaction can be made lower with the presence of an enzyme. An example of an inorganic catalyst used for this purpose is iron in the Haber process that produces ammonia which without iron would require a temperature that could not be reached without huge expense.

The same Haber process uses iron to allow the pressure of the vessel housing the nitrogen and hydrogen to be a relatively low 200 atmospheres. The biotechnology industry finds enzymes useful for the same reason.

Unlike iron, biological catalysts are very specific. Their active sites only fit one substrate and, therefore, one reaction. This might seem a disadvantage because many enzymes may be required for complex reactions but is actually good in that reactions can be tailored without unwanted products getting in the way. Enzymes are, being biological, biodegradable so less pollution stems from their use.

Enzymes are very sensitive to their surroundings though. They were of course designed to be used in cells, cells whose temperatures were not supposed to fluctuate uncontrollably. The enzyme has to be used in a body where it can work at its optimum. Too hot and the enzyme will denature; too cold and it will be too slow. If the solution is too acidic or alkaline (maybe caused by the products of the reaction being catalysed), the enzyme may again denature. A denatured enzyme is useless as it won’t catalyse any reactions.

Another problem was discovered when enzymes were first used in washing powders. Some of the people who got the proteases on their skin found that they were allergic.

However, temperature and acidity are not too difficult to control with thermometers, heaters and buffers, and enzymes can be immobilised to prevent them touching your skin.

The main problem with enzymes is that they must be purified. This is expensive, and if carried out will hopefully outweigh the cost of the reaction without the enzyme being used. In a lot of useful reactions the cost of purifying an enzyme is dwarfed by the money saved had the enzyme not been used.

Bread making is relatively simple, using enzymes twice in the process. Enzymes from the grain used to make the dough hydrolyse some of the starch into sweeter mono- and disaccharides. The main enzyme used though comes from yeast again (the word enzyme comes from the Greek ‘to leaven’, i.e., leaven bread): the yeast generates carbon dioxide and ethanol while fermenting. The bubbles of gas cause the bread to rise.

The production of beer and wine is very complex but it is the yeast that takes part in the most fundamental of the reactions, the production of alcohol.

Enzymes can also be used to speed up and reduce the temperature required for the washing of clothes. Enzymes are effective when it comes to breaking down proteins. Proteases can remove blood and grass stains, for example.

Enzymes are invaluable in technology. They have been used knowingly or not for thousands of years and will continue to be used until something that is not biological but just as good comes up.