Enzymes in Biological Washing Powder: Protease


I'm sure all of us have gotten stains on our clothes at one point or another,such as blood, gravy or egg yolk. And have you noticed how some stains are just unbelievably hard to remove? Then you see these advertisements of washing powders or detergents that will miraculously remove those stains in an instant! Wondered how these washing powders work? Read on...


Introduction to Enzymes
° Enzymes are proteins that serve as a catalyst. They are chemical agents that speed up the rate of a reaction without itself being altered in the process.
° An enzyme only binds to specific molecules as it is very selective, and the particular molecule or reactant that an enzyme works on is called its substrate.
° external image enzyme.jpg How do an enzyme and its substrate interact? Each enzyme has an active site where the substrate binds to, and it is held there to facilitate a reaction. There is a specific fit between an enzyme and its substrate, meaning that only a particular molecule will fit in the active site of an enzyme, thus each enzyme can only catalyze one kind of reaction that involves specific substrates. external image enzph.gif
° Factors such as temperature and pH can affect an enzyme’s rate of reaction because enzymes are sensitive to pH and heat. Most enzymes can only function in a particular temperature or pH range, and as the enzyme works out of its normal temperature and pH range, it will denature (change in shape so that the active site no longer fits with the substrate and the enzyme can’t function).

Use of Enzymes
clip_image001.gif Enzymes are important in regulating the chemical reactions that occur within all living organisms. Without enzymes, many of these reactions would not be able to take place at a perceptible rate.
clip_image001.gif Enzymes play an important role in the digestion of food, where large molecules are broken down into smaller molecules, and they are needed for the conservation and transformation of chemical energy.
clip_image001.gif Besides biological processes, enzymes are also useful in industrial and medical areas. For example, the fermenting of wine, curdling of cheese and brewing of beer are the result of the catalytic activity of enzymes. In medicine, enzymes are used in killing disease-causing microorganisms and promoting wound healing.
clip_image001.gif Enzymes have many uses, and now we shall take a look at the use of enzymes in biological washing powders.

external image biowash.jpgBiological Washing Powder
° What is the difference between biological washing powder and regular washing powder? Well, biological washing powder contains enzymes that help break down stains and dirt in fabrics and non-biological washing powder does not.
° It is known that many stains are difficult to remove with ordinary detergents such as blood, gravy, egg yolk, sweat or other starchy stains such as fats and grease. Heat alone only aggravates the problem of removal as they tend to coagulate and become even more firmly attached to the clothing.
° The enzymes in biological washing powders will decompose these stains easily.

Enzymes in Biological Washing Powder
clip_image001.gif The first patent for a protein-digesting enzyme was issued back in 1913, and this enzyme was extracted from animal pancreases. However, it was of limited use since it was not very stable as it was easily broken down when the detergent was used.
clip_image001.gif In the 1960s, a much more useful enzyme was obtained from a bacterium called Bacillus subtilis. This enzyme is stable in the conditions needed for a detergent wash; it could withstand temperatures up to 60°C, a high pH and the presence of phosphates and other chemicals in the washing powder. external image blood_stain_remover.jpg
clip_image001.gif Since then more enzymes have been extracted from bacteria, yeasts and other sources.
clip_image001.gif Because stains are made of different types of molecules, a range of enzymes are needed to break them down. Proteases break down proteins, so are good for blood, egg, gravy, and other protein stains. Amylases break down starches, and lipases break down fats and grease. Washing powders usually only contain one type of enzyme, though some have two or all three.
clip_image001.gif A number of the enzymes in biological washing powders are proteases which can deal with stains such as blood, egg and gravy.
clip_image001.gif The addition of an enzyme called cellulase to the washing powder breaks down micro fibrils on cotton, brightening the color of the washed clothes.
clip_image001.gif All these enzymes work efficiently at temperatures as low as 40°C

Enzyme in Specifc:
The most important enzymes used in biological washing powders is protease.
° Protease refers to a group of enzymes whose catalytic function is to hydrolyze (break down) peptide bonds of proteins. They are also called proteolytic enzymes.
° Protease digests proteins from gelatin, meat, grains & vegetable extracts, releasing amino acids and small peptides. Examples of proteases include: alcalase, savinase, esperase
° Alcalase: a proteolytic enzyme (one subset of protease) designed to hydrolyze all kinds of proteins including hemoglobin. Thus it is helpful in the removal of bloodstains as hemoglobin is the main component of red blood cells. Alcalase is readily soluble in water at all reasonable use concentrations. Alcalase is active in the hydrolysis of a wide variety of proteins.external image enyzme%20enriched%20washing%20powder.jpg
° Savinase and esperase are other subsets of protease used to remove protein stains.
° Proteases differ in their ability to hydrolyze various peptide bonds. Each type of protease has a specific kind of peptide bond it breaks. These enzymes convert their substrates into small, readily soluble fragments which can be removed easily from fabrics.


Other enzymes in Biological Washing Powder:
° Cellulase is a recent development in detergent enzymes and it is an alkaline-stable enzyme used in washing cotton fabrics. The enzyme cellulase digests the fiber cellulose, thus cellulose is also known as the substrate. Cellulase degrades the main structural components of cell wall material, thus initiating the digestion of sawdust, grass clippings, tissue etc. Therefore cellulase is helpful in removing grass stains.
° During use, small fibers are raised from the surface of cotton thread, resulting in a change in the texture of the fabric, and the brightness of colors is lowered.
° Cellulase removes the small fibers without damaging the major fibers and restores the fabric to its former condition. Cellulase also aids the removal of soil particles from the wash by hydrolyzing associated cellulose fibers.
° Lipolase: lipolytic enzyme (a particular Lipase) produced for incorporation into automatic laundry detergents. Lipolase catalyses the hydrolysis of triglycerides into more soluble materials, usually a mixture of mono- and di- glycerides, glycerol and free fatty acids. Lipolase has broad activity and promotes the hydrolysis of a wide variety of fatty substances.
° Amylase: digests starch from potatoes and grains


Process/Application of the Enzymes
° Very simply, when biological washing powder is added into the washing machine with the clothes, the enzymes in the wexternal image 9535432554353065.JPG?0.04898871191288057ashing powder will act on the various stains and substances that are embedded in the fabrics.
° The enzymes that are incorporated into the washing powder will each act on a different substance. For example, proteases will digests protein based stains, amylases will break down starches and lipases will break down fats and grease.
° Household laundering presents problems quite different from those of industrial laundering: the household wash consists of a great variety of fabrics soiled with a range of materials and the user requires convenience and effectiveness with less consideration of the cost. Home detergents will probably include both an amylase and a protease and a lengthy warm-water soaking time will be recommended. Industrial laundering requires effectiveness at minimum cost so heated water will be re-used if possible.

Why use enzymes in washing powders?
° Enzymes enhance detergent cleaning by breaking down large, hard to remove materials into smaller, easy to remove fragments.
° Proteases are the most important type of enzyme to look for when choosing an enzymatic detergent for medical use because there is a high content of protein in most body fluids (including blood, tissue and mucous) which cannot be easily removed with regular detergents/surfactants and water.
° Proteases, Amylases and Lipases are easy to obtain and only a surprisingly small amount of enzymes are needed in most detergent preparations.
° It is important to note that washing powder with enzymes work best at 40°C. One effect of incorporating enzymes in washing powders is that lower washing temperatures may be employed with consequent savings in energy consumption.

Extra Stuff:
Try a few experiements to test the effects between biological and non biological washing powders!
Hole in the Jelly
You will need:
  • Two small plastic dishes
  • Gelatine
  • Agar (you can buy agar from specialist shops like Brainwave or Experilab in Pretoria, or ask your teacher to get some)
  • An ordinary washing powder
  • A biological washing powder
external image enzyme01.gif
Read the instructions on the packets carefully and prepare two dishes of clear jelly, one of gelatine, and the other of agar.
On each jelly, put a small pinch of an ordinary powder detergent, and of a so-called biological washing powder.
The biological powder is supposed to contain an enzyme which 'removes difficult stains like egg, gravy and blood'. These contain proteins.
If this is a true claim, we would expect to find the gelatine (a protein) dissolved away under the 'biological' washing powder, but not under the ordinary powder.
The agar (not a protein) should not be dissolved by either. The jelly might soften a little for many reasons, but do not be misled by this. Look for a great hole in the jelly.
Try this experiment and see what you find. If there is a hole in the gelatine under the biological washing powder, but not one under the ordinary washing powder, then the claims of the manufacturer are true.
For more experiments:
http://www.saasta.ac.za/biosciences/enzymes.html

Sources:
http://www.school.eb.com/eb/article-2120 (A basic introduction to enzymes and its chemical nature, nomenclature and factors that affect enzyme activity)
http://www.longman.co.uk/gcsebiology/pdfs/worksheet_4_washing_powders.pdf
http://www.schoolscience.co.uk/content/5/chemistry/catalysis/catsch8pg7.html
http://www.lsbu.ac.uk/biology/enztech/detergent.html
http://www.metrex.com/learning/technicalInfo/technicalBulletins/PDFCanada/emPowerMetriZymeDetergeZyme.pdf