SALIVARY AMYLASE ACTIVITY
Enzymes are proteins that facilitate chemical reactions in cells. These are reactions
that would happen spontaneously but at a rate much too slow to support life. Enzymes
allow biochemical reactions to proceed at rates of hundreds of times per second.
Because most are proteins, enzymes are sensitive to fluctuations in temperature and
pH. Generally speaking, chemical reactions are faster as temperature increases.
However, boiling and extreme pH values denature (unravel) enzymes which
deactivates them.
Chemical reactions will proceed outside of the body and can be monitored using tests
that illustrate the presence or absence of specific molecules by changes in color.
Temperature and pH environments can be altered to determine what conditions are
ideal for enzyme activity.
Starch digestion
Most carbohydrate in our diet is provided by starchy foods. Enzymes called amylases
break apart the sugar units from starch. The first amylase to encounter food is salivary
amylase, which will break starch (the substrate) down into the disaccharide maltose
(the product) in our mouths. This explains why starchy foods begin to taste sweet
when you chew on them for a few minutes.
Tests for enzyme activity
The following demonstrations will evaluate the activity of salivary amylase on starch.
This is accomplished by monitoring the disappearance of starch and appearance of
sugar.
An iodine compound called Lugol’s reagent (IKI) can be added to a substance to test
for the presence of starch. When starch is present, it interacts with the iodine, which is
a golden color, to become a blue-black color. As starch is digested, it disappears so
that an iodine test would produce a golden color.
Benedict’s reagent tests for the presence of sugars. When heated, these sugars react
with Benedict’s reagent to produce colors ranging from yellows to oranges and reds. A
bluish green color indicates that there might only be a trace of sugar present. This
generally means that the glassware is contaminated from previous use.
, Experimental results may vary among saliva samples. Following meals, for example,
the concentration of amylase in saliva would be lowered. Additionally, there are
differences in the effectiveness of enzymes among individuals due to genetic variability.
Lab Activity
What you will need
Contents of Kit
Bottle of starch solution.
Bottle of Lugol’s solution.
Bottle of Benedict’s reagent.
Disposable pipets. These have a hash mark at 1 ml for measuring.
Test tubes.
Test tube clamp.
What you provide from home
Heat resistant mug to boil test tubes in.
A stove and small pot.
A clear glass to put test tubes in for photographs.
Tap water.
Waterproof marker or crayon.
Samples of several starchy foods such as bread, crackers, chips.
Samples of several light-colored fruits, such as apple, pear, pineapple.
Samples of a few light-colored liquids such as ginger ale, apple juice,
corn syrup, green tea.
These are the types of arrangements you’ll need to support and boil test tubes:
Enzymes are proteins that facilitate chemical reactions in cells. These are reactions
that would happen spontaneously but at a rate much too slow to support life. Enzymes
allow biochemical reactions to proceed at rates of hundreds of times per second.
Because most are proteins, enzymes are sensitive to fluctuations in temperature and
pH. Generally speaking, chemical reactions are faster as temperature increases.
However, boiling and extreme pH values denature (unravel) enzymes which
deactivates them.
Chemical reactions will proceed outside of the body and can be monitored using tests
that illustrate the presence or absence of specific molecules by changes in color.
Temperature and pH environments can be altered to determine what conditions are
ideal for enzyme activity.
Starch digestion
Most carbohydrate in our diet is provided by starchy foods. Enzymes called amylases
break apart the sugar units from starch. The first amylase to encounter food is salivary
amylase, which will break starch (the substrate) down into the disaccharide maltose
(the product) in our mouths. This explains why starchy foods begin to taste sweet
when you chew on them for a few minutes.
Tests for enzyme activity
The following demonstrations will evaluate the activity of salivary amylase on starch.
This is accomplished by monitoring the disappearance of starch and appearance of
sugar.
An iodine compound called Lugol’s reagent (IKI) can be added to a substance to test
for the presence of starch. When starch is present, it interacts with the iodine, which is
a golden color, to become a blue-black color. As starch is digested, it disappears so
that an iodine test would produce a golden color.
Benedict’s reagent tests for the presence of sugars. When heated, these sugars react
with Benedict’s reagent to produce colors ranging from yellows to oranges and reds. A
bluish green color indicates that there might only be a trace of sugar present. This
generally means that the glassware is contaminated from previous use.
, Experimental results may vary among saliva samples. Following meals, for example,
the concentration of amylase in saliva would be lowered. Additionally, there are
differences in the effectiveness of enzymes among individuals due to genetic variability.
Lab Activity
What you will need
Contents of Kit
Bottle of starch solution.
Bottle of Lugol’s solution.
Bottle of Benedict’s reagent.
Disposable pipets. These have a hash mark at 1 ml for measuring.
Test tubes.
Test tube clamp.
What you provide from home
Heat resistant mug to boil test tubes in.
A stove and small pot.
A clear glass to put test tubes in for photographs.
Tap water.
Waterproof marker or crayon.
Samples of several starchy foods such as bread, crackers, chips.
Samples of several light-colored fruits, such as apple, pear, pineapple.
Samples of a few light-colored liquids such as ginger ale, apple juice,
corn syrup, green tea.
These are the types of arrangements you’ll need to support and boil test tubes:
