HOW DOES ETHYL
ALCOHOL INHIBIT THE
RATE OF CATALYST
ENZYME ACTIVITY?
By: Jeranika Semien
INTRODUCTION:
 The general focus of this project is the study of enzymes and how
they work.
 The purpose of this experiment is to determine whether or not ethyl
alcohol can inhibit the rate of catalytic enzyme activity.
 The reason I choose this specific area to study was based on the fact
that I like to make this occur. Mixing chemicals and watching them react
is interesting to me, so, I choose to use a catalyst in hopes of enhancing
some kind of reaction in the liver.
BACKGROUND INFO..
 Enzymes are proteins that participate in cellular metabolic
processes. The basic function of an enzyme is to increase the rate of
a reaction.
 Enzymes are important because they act as biological catalysts.
This means that they bring molecules together in such a way that they
can react.
FAST FACT
 All of the reactions that they catalyze are chemically possible (at
least in theory) even in the absence of enzymes. However, in the
absence of enzymes, these reactions could not occur fast enough to
support life.
INFO (CONT’D)
 Enzymes bind temporarily to one or more of the reactants of the
reaction they catalyze. In doing so, they lower the amount of
activation energy needed and thus speed up the reaction. Catalase is
an enzyme reactant that catalyzes the decomposition of hydrogen
peroxide into water and oxygen. One molecule of catalase can break
40 million molecules of hydrogen peroxide each second.
 Carbonic anhydrase is found in red blood cells where it catalyzes
the reaction. It enables red blood cells to transport carbon dioxide
from the tissues to the lungs. One molecule of carbonic anhydrase
can process one million molecules of CO2 each second.
 In order to work, an enzyme must unite with at least one of its
reactants. In most cases, the forces that hold the enzyme and its
substrate are noncovalent. A noncovalent bond is a type of chemical
bond, typically between macromolecules, that does not involve the
sharing of pairs of electrons, but rather involves more dispersed
variations of electromagnetic interactions. Four commonly mentioned
types of non-covalent interactions include hydrogen bonds, ionic
bonds, van der Waals forces, and hydrophobic interactions. The
noncovalent interactions hold together the two strands DNA in the
double helix, stabilize secondary and tertiary structures of proteins,
and enable enzyme-substrate binding and antibody-antigen
association
OTHER INHIBITORS..
 There are many things that could inhibit a catalytic reaction. Some
this include temperature, pH, and whether or not the enzymes are in
competition with one another.
HYPOTHESIS
 The higher the concentration of the alcohol solution, the slower
the rate of the enzyme activity will be.
EXPERIMENTAL DESIGN
DIAGRAM
IV: Different concentrations of alcohol solutions
Levels:
0%
.2%
.4%
.6%
.8%
Trials:
1
1
1
1
1
DV: The rate of the enzyme activity.
C: Same amount of liver; same amount of solution;
MATERIALS
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Beaker
Water
Ethyl alcohol
6 equally cut pieces of liver
Oxygen probe
100mL graduated cylinder
6 Flasks
10mL graduated cylinder
Scalpel or knife
Hydrogen peroxide
PROCEDURES
1. Add 90mL of water and 10mL of ethyl alcohol to a beaker. Label
beaker 1% solution.
2. Add one piece of liver to a flask.
3. Once liver is added and labeled, pour in 100mL of solution.
4. Measure 10mL of hydrogen peroxide and add to the flask.
5. Quickly attach the oxygen probe to the flask.
6. Press Start on the Logger Pro programing option.
7. Give flask a final whoosh and allow it to collect data for 5
minutes.
8. Repeat steps 1 thru 7 for remaining solutions of concentration.
DATA
ANALYSIS..
 The data received from this experiment varies too much to make conclusive
generalizations. I hypothesized that the concentration of the alcohol solution was directly
related to the reaction rate of the enzyme; the higher the concentration level, the slower
the reaction time will be. The data collected from this experiment does support my
hypothesis but the data varies too much to conclude that it is accurate. The data was
collect for a period of 5 minutes. It took the .2% solution 4.75 min +/- .25 min to reach
33.01 which is the maximum amount of oxygen that was able to be created with the given
circumstances. It took the .4% solution 3.50min +/- .25 min, .6% solution 4.75 min +/.25 min, .8% solution 3.00 min +/- .25 min, and the 1% solution 2.25 min+/- .25 min.
LIMITATIONS
 I thought that by conducting this experiment a steady correlation between
concentrations would be made. For example, as the concentration increases, the reaction
time decreases (my hypothesis) or even an opposing theory, like as the concentration
increases, the reaction time is faster. Instead, I received what seemed to be a scatter plot
of data. No exact correlation could be made. This can be due to human errors and flaws
within my experiment. Although I tried to keep it as close to the time as possible, the time
it takes to pour in the alcohol, attach the probe, and press start on the lab pro software
varied approx. +/- 4.00 sec. Also, the measurements of the solutions may have been off
by +/- .05 mL. All of these things could have affected the array of different figures
collected.
CHANGES
 One thing that I learned from conducting this experiment is that that there are
many things that can inhibit the reaction time of an enzyme. These things include
temperature and pH. In hopes of actually attaining conclusive data, a few
adjustments can be made. The first thing I would change is the way I collected the
data. Instead of using the oxygen probe, I would use the stopper and syringe
method. This means that a stopper would be attached to the flask and the syringe to
a cord. As oxygen is formed, it would cause the syringe to move. I would then
record the oxygen displaced by reading the number on the syringe.
WORKS CITED
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Enzymes.html
http://en.wikipedia.org/wiki/Enzyme
http://www.biology-online.org/dictionary/Catalyses
http://chemistry.about.com/od/chemistryglossary/a/reactantdef.htm
http://hyperphysics.phy-astr.gsu.edu/hbase/chemical/oxred.html
Practice and theory of enzyme immunoassays: Volume 15 - Page 358