Effects of Salivary Amylase
By Nena Vance

Part A:

What does the enzyme, amylase do?

Enzymes cause various reactions in the body to happen, also called diastase.

Things that we eat are broken down once in the mouth organ. What happens and how does it happen? Amlyase is an enzyme that breaks down starch to sugar. The amylase in the mouth, salivary amlyase, is called ptyalin. Ptyalyn can do digestive can work in the stomach for several hours. Iodine and Benedict’s solution is used to recognize starch and sugar (maltose) in our saliva. The group experiment that was completed in class shows that it is accurate.

How does amylase work?

Amylase, like other enzymes, works as a catalyst. All catalysts are enzymes, but not all enzymes are catalysts. A catalyst is a substance that causes a chemical reaction to break down other substances, but the catalyst does not become a part of the end product of that reaction. Amylase digests starch by catalyzing hydrolysis, which is splitting by the addition of a water molecule. Therefore starch plus water becomes maltose (which is equivalent to two joined glucose molecules). Body temperature is the optimal heat for the best reaction of amylase.

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Materials Needed & Methods:

Benedict’s Solution

  1. 173 gm crystalline sodium citrate
    100gm anhydrous sodium carbonate
    800 mL dH2O /(NaCO3)
    Mix and filter if needed.

  2. 17.3gm copper sulfate (CuSO4)
    100mL dH2O
    Mix together and add to Part A.

    Add dH2O to bring volume to 1 liter.

Gram’s Iodine

          300 mL cool dH2O
          2gm potassium iodide (KI)
          1 gm iodine crystals (I2)
          Mix and let iodine dissolve,

                    OR---

          30mL 0.1 N iodine solution
          q.s. to 100 mL with dH2O
          (0.1N= 12.7 gmI2+ 20.0 gm KI per liter)
          KEEP TIGHTLY CAPPED!

          Recipes: (Carter, J. S. Stein, 1994)

Benedict's Reagent Solution

Benedict’s Reagent is a deep blue colored, alkaline liquid used to test different chemicals. Since simple sugars, for example maltose, have a positive reaction to Benedict’s Solution, it is used as an indicator in experiments that test the presence of sugar.


Students in the group needed a 10mL-graduated cylinder to gather 1mL of saliva. Then adding 4 mL of dH2o to the saliva to dilute it to a total of 5mL. The solution was mixed with the vortex and collected in a 100mL beaker.

Five 16x150 test tubes and a rack were needed. Each test tube was labeled with a waxed pencil, 1-5. The tubes were then filled with specified solution:

After filling the tubes, 5 drops of Gram’s iodine was added to each. Recording of any reaction was written, and the tubes and rack was set in the incubator at37*C for about 30 minutes. # 5 tube was to be watched closely for any color change.

The test tubes were then heated over a Bunsen burner until warm. Using a Pasteur pipet, 10 drops of Benedict’s reagent was added while still heating over the Bunsen burner. Students watched for any color change and recorded them.

Time for clean up.


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Data/ Results:

Literature Review:

The mouth -site of initial digestion, chewing, swallowing , moistening of food from saliva, amylase- an important enzyme that breaks food down into carbohydrates. ( Bealer’s notes. 4/20/05. Available: http://www.mecca.org/LOC/QUESTIONS).

Starch digestion begins in the mouth with enzymes that are secreted in saliva. You add a drop of iodine solution, and it produces a dark blue color, indicating the presence of starch. Enzymes are proteins. Temperature can effect them. It is denatured. Enzymes must fit with their substrate in order to work. If an enzyme is denatured, it cannot fit anymore. An enzyme that cannot fit, cannot do its job.( Amylase Pre-and Post Lab Activities. Available : http://www.oxy.edu/departments/tops/Amylase/amylpre-post.htm). The effects of salivary amylase on starch can be demonstrated by mixing saliva with a starch solution. (Vance, Nena. Lab notebook. P 115).

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Summary:

Experiment A was a test to analyze the effects of salivary amylase. The results of the tests show that Amylase breaks starch down into sugar. It is wondered if the results were altered in some way because of the saliva donator, was actually chewing gum before the donation. This means more sugar than expected.

Test tube #2 & 5, had similar reactions to the iodine, and strong to moderate reactions with adding the Benedict’s reagent. What is to believe with the other test tubes? Could it have been the enzyme in the saliva breaking starch into sugar? This experiment can also be done by using oyster crackers.

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Bibliography;

Campbell, Mitchell, Reece. Biology ....Concepts & Connections, 3rd Edition. Benjamin/ Cummings: S.F. California, 1994

Amylase Pre-and Psst-lab Activities. 11/18/99. Internet Available: http://www.oxy.edu/departments/tops/Amylase/amylpre-post.htm

Bealer’s notes, 4/20/95. Internet. Available: http://www.mecca.org/LOC/QUESTIONS/notes042095.html

Enzyme. 11/ 1999. Internet Available: http://biology.clc.uc.edu/students/114-fall96/Amy--bec.htm

Encyclopedia Entry. 11/18/99.Internet. Available: http://cbs.infoplease.com/search.php3?query=amylase&in=encyclopedia&go=Go%21

Carter, Jan "Enzymes" Clermont U.C. Bio lab. Wed./Fri. 8:30, 3 Nov.1999.