This lab will examine the specificity of an enzyme (lactase) to a specific substrate (lactose). You and your lab partner will observe the actions of the enzyme and how shape is important to enzyme reactions.
Lactose, the sugar found in milk, is a disaccharide composed of glucose and galactose (both six-sided sugars). Sucrose, ordinary table sugar, is also a disaccharide composed of fructose and glucose. Glucose is a six-sided sugar and fructose is a five-sided sugar.
Lactase is an enzyme that breaks lactose down into galactose and glucose. Lactase can be purchased in pill form by people who are lactose intolerant. These people lack the enzyme, lactase, and cannot break down the sugar lactose into its component parts. Although lactose is similar to sucrose, lactase will break down only lactose because of the shape of the sugar. In this lab, you will see lactase break lactose down into galactose and glucose. You will also observe what happens if the shape of lactase enzyme is changed due to heating or a change in the pH. Procedures--Solution preparation
1. Enzyme solution: Place one lactase tablet into a mortar and pestle bowl. Grind the tablet until it is a fine powder. Add the entire contents of the bowl to two hundred milliliters of water which is in a medium sized beaker. Stir until the powder has dissolved in the water.
2. Your milk product
3. Denatured enzyme solution: Place twenty milliliters of enzyme solution into a small beaker (100 mL size). Add two hundred milliliters of water to a four hundred milliliters Pyrex beaker. Place the beaker on the hot plate. Boil the water/enzyme solution in the beaker for thirty minutes. Let the solution cool to room temperature.
1.Label the small 100 mL sized beakers with the following labels:
Beaker A with your milk product and enzyme solution.
Beaker B with your milk product and denatured enzyme solution.
2. In Beaker A add twenty milliliters of your milk product and ten milliliters of enzyme solution. Immediately begin to time the reaction, using increments of five (5) minutes and test for glucose with the Diastik. Remember that enzyme reactions occur very quickly. Record this data in your data table. If there was glucose present mark a ‘+’ in the table. Additionally, mark the numeric