Name: ____________________________________ Date: _____________________ Sec: ______
Enzyme Concentration Lab
Background: Enzymes are proteins that speed up the rate of chemical reactions that would otherwise
happen more slowly. The enzyme may be altered, but it is not consumed by the completed reaction. You
have hundreds of different enzymes in each of your cells. Each of these enzymes is responsible for one
particular chemical reaction that occurs in the cell.
Hydrogen peroxide is a chemical used to treat wounds. It is an effective antiseptic because it is deadly to
cells. Of course, the cells that you want to destroy are bacterial cells that may enter an open wound, not
your own cells.
So you may be surprised to find out that hydrogen peroxide is produced as a waste product in every cell of
your body. The enzyme, catalase, which is found in the cells of many living things, speeds up the reaction
that breaks down hydrogen peroxide into two harmless substances – water and oxygen.
2H2O2 2H2O + O2
In this reaction, hydrogen peroxide is the substrate. The rate of this reaction can be determined by
measuring the amount of oxygen produced by the reaction. Filter paper disks that normally sink in water
will rise as oxygen gas bubbles accumulate in the small spaces in the paper. Sinking a paper disk in a
solution containing both hydrogen peroxide and catalase results in the production of oxygen gas (see
chemical equation above). Thus, the rate at which the paper disk rises can be used to measure the rate of
the reaction.
Problem: How does enzyme concentration affect the rate of a chemical reaction?
Hypothesis: _________________________________________________________________________
Materials:
spot plate
small beaker of water
forceps
stop watch
small beaker of potato enzyme (catalase)
small beaker of H2O2
4 small discs of filter paper
3 droppers – labeled water, peroxide, and catalase
Procedure:
1. Place 1 ml of hydrogen peroxide into each of the top four depressions of your spot plate.
2. Place 1 ml of 100% catalase into the first depression in the second row of your spot plate.
3. Make 50% dilutions as shown below: **this goes in the second row of dots
1 ml of
enzyme
100% enzyme
First spot in the
second row
.5ml of
previous
spot + .5 ml
water
50% enzyme
Second spot in
the second row
.5 ml of
previous
spot + .5 ml
water
25% enzyme
Third spot in
the second row
.5ml of
previous
spot + .5 ml
water
12.5% enzyme
Fourth spot in
the second row
<<<<READ THE FOLLOWING BEFORE PROCEEDING>>>>
4. Place a paper disc into each of the enzyme % depressions.
5. Use the forceps to pick up the filter paper discs in the 100% enzyme. Hold the forceps as close to
the edge of the disc as possible.
6. Drop the disc into the BOTTOM of the hydrogen peroxide depression directly above it.
7. Begin timing IMMEDIATELY (as soon as the disc touches the hydrogen peroxide.
8. Stop timing when the disc rises back to the surface.
9. Enter your data in the table.
10. REPEAT steps 5-9 for each of the depressions. The enzyme soaked disc always goes into the
hydrogen peroxide depression DIRECTLY above.
11. After completing the all of these steps – add 1 ml of hydrogen peroxide into an empty depression.
12. Soak a filter paper disc in water and drop it into the hydrogen peroxide depression. Time how long
it takes the filter paper disc to sink and rise…if the time is longer than 3 minute (180
seconds)…STOP timing and enter the 180 seconds into the table. This is 0% enzyme.
13. Wash your spot plate. Dry it. Return it to the original location.
TABLE
% Catalase
Enzyme
Discs/min
(60/sec for disc to rise)
These are the top four depressions with
hydrogen peroxide in them
100%
50%
25%
12.5%
0%
These are your different % enzyme
depressions.
Analysis
The independent variable that you had control over was _________________________ so it goes on the
____ axis.
The dependent variable that you were measuring was ____________________________
so it goes on the _____ axis.
1. Now create a graph that shows the relationship between enzyme concentration and the rate of the
reaction.
2. Does the data support your hypothesis? Why or why not?