Austin Peay State University Department of Chemistry Chem Enzymes and Starch

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1 Purpose Demonstrate how enzymes act as proteins as well as to facilitate reactions. Introduction Almost all biological materials are made up of specific groups of compounds, such as fat, protein, and carbohydrates. The most versatile of these is protein, which is used for a variety of different functions. Protein makes up many different parts of our body including our hair, finger nails, cartilage, and skin. Proteins also exhibit a wide range of physical properties. For example, a raw egg has a clear and runny white made of albumen, a protein. When cooked, the proteins in the egg white turn into a soft opaque solid. Some proteins are resilient to heat while others are very sensitive to heat. Proteins also have both hydrophobic and hydrophilic properties. As a result, they are commonly used as emulsifiers. When you do not want a mixture of oil and vinegar in your In a salad dressings to separate, you may add protein to emulsify the mixture and make it homogeneous. One important function of proteins is as enzymes. Enzymes are catalysts that help facilitate reactions important to the function of life. They are used to help break down fat, aid in digestion, and heal wounds. Enzymes are also common to industrial and commercial applications. They are found in detergents to help clean your clothes, used in fruit juice processing to create a clear juice, and involved in making corn syrup. Corn syrup comes from of another common biochemical, the carbohydrate. Starch is a carbohydrate that is a polymer of glucose molecule that has a large branched structure similar to a tree. In its dry form starch coils up in granules, but when heated up in water, the starch molecules unravel and tangle with each other causing the solution to turn into a gelatinous mixture. The enzyme we will be using today is alpha amylase, an enzyme that cuts off the branches of the starch turning the branched molecule into a mixture of thread like polymers. The cut starch molecules no longer tangle with each other and the physical properties change. When the enzyme acts on the starch molecule, the mixture will go from a gel like solution to a viscous liquid similar to thinner diluted syrup. In this experiment we will subject the enzyme to different conditions, varying temperature and ph, to demonstrate how the conditions influence enzyme activity. Revision F10 IB Page 1 of 7

2 Procedure 1. Obtain 5 clean 250 ml beakers. Label the beakers To beaker 1, place 100 ml of distilled water and 20g of starch. Stir with a mixing rod to make sure none of the starch is sticking to the bottom. 3. Place the beaker on a heating stir plate with a stir bar and starting stirring at 300 rpm with the heat on 275 C. 4. Record your observations at the beginning of heating and every utes for utes; this is your control experiment. Keep beaker 1 for comparison with the other conditions. 5. In beaker 2 place 100 ml of distilled water and 20g of starch. Stir with a mixing rod to make sure none of the starch is sticking to the bottom. 6. Obtain 1 clean 50 ml beaker. Add 5 ml of distilled water and 5 drops of alpha amylase and thoroughly mix by swirling. 7. At 1 ml of diluted enzyme solution (step 6) to beaker Place the beaker on a heating stir plate with a stir bar and starting stirring at 300 rpm with the heat on 275 C. 9. Every minute, note the color and consistency of the solution. 10. Record your observations at the beginning of heating and every utes for utes. If the solution becomes too difficult to stir, you may stop. 11. Repeat steps 5-10 for beaker 3. In step 6, replace distilled water with 2.0 ph buffer solution. 12. Repeat steps 5-10 for beaker 4. In step 6, replace distilled water with 10.0 ph buffer solution. 13. Repeat steps 5-10 for beaker 5. After step 6, boil the enzyme dilution to a boil before adding it to beaker 5. Waste Disposal Pour all solutions down the sink with an excess of water. Clean-Up Wash all glassware with soap then rinse 3 times with tap water, and once with deionized water. Revision F10 IB Page 2 of 7

3 Beaker 2: Normal enzyme Beaker 1: Control (no enzyme) Austin Peay State University Department of Chemistry Chem 1041 Data Sheet 1 Name: Lab Partner: Time Observations Revision F10 IB Page 3 of 7

4 B Beaker 4: Enzyme in ph 10.0 buffer Beaker 3: Enzyme in ph 2.0 buffer Austin Peay State University Department of Chemistry Chem 1041 Data Sheet 2 Time Observations Revision F10 IB Page 4 of 7

5 Beaker 5: Boiled enzyme Austin Peay State University Department of Chemistry Chem 1041 Data Sheet 3 Time Observations Summary Observations Beaker 1 Beaker 2 Beaker 3 Beaker 4 Beaker 5 Conditions Results (gel or liquid) Was Enzyme Active? Revision F10 IB Page 5 of 7

6 Post-lab Assignment Name: 1. Compare the results from the different trials. What did you notice about the results between the different way the enzymes was treated? Which conditions rendered the enzyme inactive? 2. Given the conditions you saw in the experiment, what are some conditions in a processing plant that are important to maximizing enzyme efficiency? Revision F10 IB Page 6 of 7

7 Name: 1. Why are proteins so varied in properties and functions? Pre-lab Assignment 2. Give 5 examples of how enzymes are used in day to day life. 3. A major component of corn syrup is glucose, sugar that is the basis for starch. The enzyme we are using is part of the process to make corn syrup. What kind of enzyme would also be needed in the process of going from starch to glucose. Revision F10 IB Page 7 of 7