Advertisements for some detergents proclaim that their product is a miracle worker in a box. What is the ingredient in some detergents that makes them so effective at removing stains?
In this project, you will analyze the chemistry of enzymes, which are the chemicals added to detergents that make them such miraculous cleaners. You will examine the effect of water temperature and pH on the effectiveness of detergent enzymes. You will also determine the effectiveness of enzyme detergents on cleaning different stains.
Purpose: To determine the effect of the enzymes found in a detergent on a protein.
- twelve 1-quart (1-liter) jars
- distilled water
- marking pen
- masking tape
- 1-tablespoon (15-ml) measuring spoon
- powdered laundry detergent without enzymes (Ivory Snow)
- stirring spoon
- powdered laundry detergent with enzymes (such as Cheer)
- 12 eggs (fresh, hardboiled, and peeled)
- magnifying lens
CAUTION: When preparing the boiled eggs, wash your hands and any utensils used when handling the uncooked eggs. Raw eggs can contain a harmful bacteria.
- Fill the jars three-fourths full with distilled water.
- Use the pen and tape to label and number the jars "Control-1," "Control-2," "Control-3," and "Control- 4"; "With-1," "With-2," "With-3," and "With-4"; and "Without-1," "Without-2," "Without-3," and "Without-4."
- Add 1 tablespoon (15 ml) of detergent without enzymes to each of the four jars labeled "Without." Stir.
- Add 1 tablespoon (15 ml) of detergent with enzymes to each of the four jars labeled "With." Stir.
- Divide the jars into four sets of three jars each. Each set will contain jars labeled "Control," "With," and "Without."
- Observe and record a preliminary qualitative description of each egg in an Enzyme Data table, like Table 28.1. Then place one egg in each jar.
- Stand the jars together in an area away from drafts or direct sunlight and with relatively constant temperature.
- For 7 days, make daily observations of the surface of the eggs. Each day, lift one of the eggs out of its jar, use the magnifying lens for close-up inspection, then replace the egg in its jar. Repeat this procedure for each egg. Make a point not to disturb the surface of the egg any more than necessary during the examination.
The surface of each egg is smooth before being placed in the jars. For each set, as time passes, the surface of the eggs in the detergent with enzymes looks rough and may have a cratered appearance. But those in the detergent without enzymes, as well as the control, remain smooth.
Catalysts are chemicals that change (either speed up or slow down) the rate of a chemical reaction. Enzymes are biological catalysts, which means they are found in organisms (living things). The substance on which an enzyme acts is called a substrate. The specific part of an enzyme that attaches to a substrate is called the active site. Enzymes are proteins, which are any of a large number of complex organic compounds (chemicals containing carbon and found in living organisms) that make up living organisms and are essential to their functioning. Enzymes are different from other proteins because they cause a chemical change, which usually involves the forming or breaking apart of the substrate.
Enzyme action involves three basic steps: First, the enzyme binds to the substrate, then the chemical reaction occurs, and finally the changed substrate is released from the enzyme (see Figure 28.2). Enzymes are usually named after what they bind to (the substrate), followed by the suffix ase. So the enzymes in detergent that break apart proteins are called proteases. Proteases change larger protein molecules in the egg into smaller molecules, causing the egg to break down. Some proteins, such as hemoglobin, exhibit color because they contain metals. Hemoglobin, for instance, is a blood protein and is red due to the iron attached to it. Proteins are made up of long twisted molecules, which can wind through the fibers of cloth and bind to them. In your wash, the proteases in laundry detergent break down protein, such as hemoglobin, thus making it easier for the water and detergent to wash the stains away. Stains that are not caused by colored proteins may not be affected by the proteases.