Enzymes and Detergents
Today’s lab will focus on enzymes in detergents. These enzymes are purposefully put
into our cleaning solutions in order to help break down organic matter such as dirt or
food. Some common enzymes include:
Enzyme
Protease
Amylase
Lipase
Guardzyme
(Peroxidase)
Function
Digests protein-based stains
Digests starch-based stains
Digests fat or oil-based stains
Carezyme
Removes fuzz build up on cotton
Inhibits dye transfer
We will look at different detergents with and without enzymes (and our unknown) to
determine if the presence of enzymes in detergent actually breaks down (degrades)
proteins better than detergents without enzymes. We will also test to see if the
concentration of enzymes has any effect on protein digestion and if pH and temperature
effect enzyme activity. All of these activities will be done if test tubes of gelatin (our
protein source). After setting up all your test tubes, the reaction needs about 24 hours to
react. Therefore, at least one person per group needs to come back to lab the next
day and measure their results.
Work in groups of four and be meticulous about labeling all your test tubes. Make sure
you all understand how we are going to measure the tubes (be able to identify millimeters
as opposed to centimeters on your rulers).
Crime Scene Implications: There was detergent left at the scene of the crime when
someone apparently tried to clean up a blood stain. We are going to attempt to determine
if this detergent contained enzymes or not, and then we will send our sample to chemistry
for further analysis.
Day 1
Part 1: A Survey of Various Laundry Detergents: Enzymes vs. No Enzymes
1. Each group will obtain 6 non-labeled test tubes containing gelatin. Label the test
tubes 1-6 and your initials (or group name). Place the test tubes in a test tube rack.
2. Take the following five detergents to be tested; Ward’s Detergent with Enzymes,
Ward’s Detergent without enzymes, Tide with Bleach, Cheer with Enzymes and
Unknown. Test tube six will be your control tube containing only water. (see Table 1 for
order).
3. Remove the “1” test tube from the test tube rack. With a sharpie marker, mark the
level of the gelatin in this tube with a small thin line (mark the level all the way around
the tube so it is visible from all sides).
4. Place the bottom of the tube on a flat surface (your lab bench) and with a ruler,
measure in millimeters from the tabletop to the marker line. Record this measurement in
the “Initial Height” column of Table 1. Place test tube “1” into the test tube rack.
5. Repeat steps 3 and 4 with test tubes “2”, “3”, “4”, “5”, and “6”.
6. Begin with the detergent that is listed as “1” on Table 1. Draw up 1 ml of this
detergent and place it into your test tube labeled “1”. Make sure you use only the
designated pipet for this detergent because you do not want to cross-contaminate the
detergents you are working with.
7. Place the test tubes into the test tube rack.
8. Repeat steps 6 and 7 with detergents 2, 3, 4, 5, and 6 from you list.
9. Cover your test tubes with a piece of plastic wrap to avoid contamination.
Part II: Using Ward’s Detergent with Enzymes to Test the Effect of Enzyme
Concentration on Protein Digestion
1. Obtain 5 non-labeled test tubes containing gelatin and label them 0%, 25%, 75%, and
100%. Also label each test tube with your initials or group name. Place the test tubes
into a test tube rack (you can still use the same one from part I if there is room).
2. Remove the 0% test tube. With a sharpie marker, mark the level of the gelatin in the
test tube with a small line.
3. Set the test tube on your lab bench and with a ruler, measure in millimeters from the
tabletop to the marker line. Record this measurement in the “initial height” column of
Table 2. Replace the 0% test tube in your test tube rack.s
4. Repeat steps 2 and 3 with test tubes 25%, 50%, 75% and 100%.
5. Begin with your 0% test tube. With the designated disposable pipet add 1 ml of the
0% solution to your corresponding test tube. Again, use only the designated pipet for
each separate solution.
6. Repeat step 5 for your test tubes 25%, 50%, 75% and 100%.
7. Cover your test tubes with a piece of plastic wrap to avoid contamination.
Part III: Using Ward’s Detergent with Enzymes to Test the Effect of pH and
Temperature on Enzyme Activity.
1. Obtain 8 labeled test tubes: two pH 4, two pH 6, two pH 8 and two pH 10.
2. Label one from each pair L for low temperature and H for high temperature. Also put
your initials or group name on each test tube.
3. Mark the level of gelatin in each of the 8 test tubes like you have done with the two
previous experiments.
4. Measure the level of gelatin in each of the 8 test tubes like you have done with the two
previous experiments. Put the results of your measurement in the Initial Height column
of Table 3.
5. Add 1 ml of the appropriate Ward’s Detergent with enzymes to each test tube (i.e. pH
4 should go in both pH 4 test tubes).
6. Put the pH4-L, pH 6-L, pH 8-L, and pH 10-L in it’s own test tube rack. Cover with
plastic wrap.
7. Place the low temperature test tubes in the refrigerator. The high temperature will
remain at room temperature.
Day 2
Part I: A Survery of Various Laundry Detergents: Enzymes versus no enzymes.
1. Obtain your six test tubes from Part I. Observe the test tubes closely for liquefied
gelatin. The liquid gelatin is a result of protein degradation. You should be able to note a
distinct interface between the liquefied gelatin/detergent mixture and the solid gelatin.
2. Remove test tube 1 from your test tube rack. With a sharpie marker, mark the
interface between the liquid gelatin/detergent mixture and the solid gelatin.
3. Set the tube on your lab bench and with a ruler, measure in millimeters from the
tabletop to this marker line. Record this measurement in Table 1 in the Final Height
Column. Replace the test tube into the test tube rack.
4. Repeat Steps 2 and 3 for you remaining test tubes, 2, 3, 4, 5, and 6.
5. In order to determine the amount of gelatin that was degraded by each detergent,
subtract the final height from the initial height for each test tube. Enter these calculations
in the “Change of Height” column in Table 1.
Part II: Using Ward’s Detergent with Enzymes to test the Effect of Enzyme
Concentration on Protein Digestion.
1. Repeat what you just finished for Part I, using the Part II test tubes. Enter your values
into Table 2.
Part III: Using Ward’s Detergent with Enzymes to Test the Effect of pH and
Temperature on Protein Digestion.
1. Repeat what you just finished for Part II, using the Part III test tubes. Enter your
values into Table 3.
2. Dispose of all test tubes in the appropriate labeled bins.
Table 1
Effects of Detergents on Protein Digestion
Type of
Detergent
Does It Initial Final Change in Height
Contain Height Height
(mm)
Enzymes (mm) (mm)
Ward’s
Detergent
w/Enzymes
Ward’s
Detergent
w/o
Enzymes
Tide with
Bleach
Cheer
Unknown
Control
(Water)
Table 2
Effects of Enzyme Concentration on Protein Digestion
Concentration of
Initial Height Final Height Change in Height
Ward’s Detergent with
(mm)
(mm)
(mm)
Enzymes
0%
25%
50%
75%
100%
Table 3
Effect of pH and Temperature on Enzymatic Protein Digestion
Detergent with Initial Height Final Height Change in Height
Enzymes
(mm)
(mm)
(mm)
pH 4
Low Temperature
40C- 100C
pH 6
pH 8
pH 10
pH 4
pH 6
High Temperature
200C- 250C
pH 8
pH 10