Activity 1:
The Effects of Temperature and Inhibitor
on the Enzyme Catalase Extracted from Potato
Introduction
Catalase is an enzyme found in fairly high concentration in
several fruits and
vegetables. Its specific action is to decompose hydrogen peroxide
into water and
oxygen gas. This enzyme is also found in animal blood, and
accounts for the ‘‘fizzing”
when hydrogen peroxide is placed on an open wound. When the
temperature is
increased, the activity of enzymes also increases. However, a
temperature is eventually
reached where the protein enzyme is denatured and is no longer
active. Enzymes can
be inhibited by many substances. Catalase is inhibited by the
copper(II) ion.
Purpose
To show that an enzyme can be isolated from a simple source, a
potato, and that the
activity of the enzyme depends upon temperature. To show that
copper(II) ion is an
inhibitor for the enzyme catalase.
Safety
1. Wear protective goggles throughout the laboratory
activity.
2. Observe general safety rules when conducting this
activity. None of the
materials or solutions pose unusual safety hazards or require
special handling.
NOTE: There are two alternate procedures for this activity.
Your teacher will tell you
which one to do.
Procedure A: Measuring Height of Foam
Produced by Catalase
Procedure
1. Place potato pulp in a 50-mL graduated cylinder to
a depth of about 3 cm.
2. Add 10 mL 3% hydrogen peroxide. Stir the cylinder
quickly to mix the pulp
and the hydrogen peroxide.
3. Note the time that a foam begins to form.
4. After 1 min, measure the height of the foam (from
the top of the liquid to the
top of the foam)
5. Measure and record the foam height each minute for
at least 5 min.
6. Construct a graph that will allow you to record
foam height on the y-axis and
time on the x-axis. Label this Graph 1.
Effect of Temperature on Foam Height
1. Add potato pulp to a depth of about 3 cm to a
second graduated cylinder and
place the cylinder in a water bath for 2 to 3 min. Your
teacher will specify the
temperature for your water bath. Record the temperature.
2. Add 10 mL 3% hydrogen peroxide to another
graduated cylinder.
3. Place both cylinders in a water bath for 5 min. Your
teacher will specify the
temperature for your water bath.
4. Remove both cylinders, quickly pour the 3%
hydrogen peroxide into the
potato pulp. Put the cylinder back into the water bath. Measure
the foam
height after 5 min and record your data.
