Why Are The Enzymes In Washing Powders Not Destroyed By High Washing Temperatures?

Enzymes are proteins which increase the rate of reaction in the breakdown of certain substances. These are added to detergents so that they can break down tough stains into substances that can easily be dissolved in water and be washed off with it.
Proteins have a certain range of temperature at which they work best. Beyond this range, they either become inactive or they are denatured.
Denaturation commonly occurs at high temperatures, which is why washing powders that contain enzymes should be used at low temperature. Usually, the best temperature is around 37^oC which is  also the temperature of a human body.
When the temperature is increased beyond a certain point, the bonds within the enzymes start to break. As a result, the structure of the enzyme molecule changes. If the structure of the enzyme, especially its active site, changes, the substrate molecules are no longer able to bind to the enzyme. If it does not bind to the enzyme, the rate of reaction does not increase and the stain does not break down. Therefore, you would be destroying the enzyme part of the washing powder of you increase the temperature. If the enzymes are destroyed, the washing powder is no longer more effective than any other detergent available in the market which is without enzymes.

Having washing powders that contain enzymes ~ the biological variety of washing powder ~ has only been possible in the last 25 years or so. Enzymes that degrade fatty spots and dirt in clothes that need washing usually work at physiological temperatures ~ somewhere around 37 degrees Celsius.

Research into washing powder development therefore concentrated on enzymes from bacteria that could survive much higher temperatures. These so-called heat loving bacteria are used to living at very high temperatures, some approaching boiling point, in their natural habitats in hot volcanic springs.

Heat loving bacteria have thermostable enzymes that are more resistant to other harsh conditions such as extremes of Ph and to the presence of organic solvents. Perfect for the washing machine!

The genes that code for thermostable enzymes were isolated from their host bacteria and genetically engineered into ordinary bacteria to ensure a big supply for commercial use. One example is the alkaline protease subtilisin, found in the bacterium Bacillus subtilis.