Finding out how these different enzymes operate and react are essential in our lives. Enzymes are efficient and "the mild conditions in which they work and their high biodegradability, enzymes are very well suited for a wide range of industrial applications," Learning about these three enzymes will create a clearer picture of their many functions.

In order to show how these enzymes react with the change in temperature, starch, and acid pH, a series of experiments will have to be made. Hopefully, these experiments will help educate and show how different enzymes function

Literature Review

(Collier's Encyclopedia, 262). The catalytic activity of an enzyme depends on its amino-acid sequence and its tertiary structure.

In 1889, Svante Arrhenuis said that a catalyst acts as follows: it first forms a compound with the reactant or subtrate; then, the compound enters the transition stage; finally, the compound breaks down into a catalyst (Academic American Encyclopedia, 213). The catalysts are capable of aiding in a reaction many times over. The equation for enzyme catalysis, sometimes known as Michaelis-Menton equation, is ... Enzyme + Subtrate = Enzyme Subtrate - Enzyme + Product (Collier's Encyclopedia, 263).

There are a few factors that affect enzyme activity. One of these factors is temperature. If the temperature is too high (around 50-60 degrees C\ 122- 140 degrees F) the enzyme activity increases as the temperature does. Another factor is acidity; an enzyme can only work within a given range of its pH. If temperature and acidity are kept steady, the amount of enzyme activity in an enzyme system is made up by a concentration of enzyme and subtrate.

When large enzyme molecules are performing catalytic activity, there is sometimes a need for coenzymes or enzyme factors. (In cellular enzyme activity vitamins and minerals have the role of coenzyme).

A number of diseases also involve enzyme activity. An example of this is Phenylketonuria, this disease is resulted from an abnormality of the enzyme phenylalanine hydroxyls. This disease causes brain damage and mental retardation, mostly in newborns.

Materials and Methods

The first experiment was to test the effects of temperature on enzyme activity of bromelain. Fresh pineapple juice and cooked pineapple juice was added to separate test tube groups; four present with gelled jello and six present with 1cm cube of egg white, and then divided into sub- groups to be put into different temperature conditions.

The second experiment was to test the effects of pH on catalase activity. Cabbage juice was used in conjunction with peroxide to show catalase activity. Substances with different pH levels were mixed with cabbage juice, and then peroxide was used to test the catalase activity in these mixtures.

The third experiment was to test the effects of salivary amylase on starch. Gram's iodine solution and Benedict's solution were used to test the presence of starch and maltose in five test tubes of various substances. These solutions were also used to show the salivary amylase had changed starch into maltose.

First , 10mL of saliva was collected and diluted to 100mL , in a 100mL graduated cylinder.


The results of the first experiment produced different reactions. The following results are from the jello sub-group. In test tube 1, the jello was liquefied. Test tube 2, showed no reaction. In the third test tube, there was only a slight liquefaction of the jello. The fourth test tube in this group produced no reaction.

The second sub-group involving the eggs created varied results as well. Test tube 1 showed a slight disappearance of the egg. Test tubes 2, 3, and 4 showed little or no change in the reactions to this experiment. In test tube 5, the egg had completely disappeared. In the final test tube, the egg was almost completely gone.


In the first part of the experiment, the Jello, showed just how enzymes work. Jello contains protein and enzymes break down protein. When the enzyme in the pineapple juice was fresh and noting in the way of denaturing was done to it the enzyme broke down the protein in the jello a lot more than in the other groups that had the boiled enzyme. This proved that enzymes do break down proteins and when the enzyme is denatured the enzyme does not work as well any more.

In the next experiment with the use of cabbage juice as an pH indicator, it was found that the catalase in cabbage that broke down the peroxide that was added has a better reaction in a certain range pH. It was found that in the tubes that had a pH of 6 and the cabbage juice in it had a strong reaction. This means that the catalase in cabbage juice that breaks down the peroxide works best in this pH. This also suggests that the pH has to be neutral or close to it to work correctly.

In the final experiment it was concluded that saliva turns starch into sugar. When the benidicts solution is added to a solution it is testing for the presents of sugar. It was found that when the solution was added to the test tube with saliva and starch the solution eventually made the formula turn a yellow color, thus indicating the presents of maltose sugar. So it was concluded that saliva turns starch into sugar.

It was found that all of the hypothesis that were assumed in the first parts of the experiments were true. All of the information given was proven by the experiments done. There other experiments that could be done concerning the use of catalase in the human body. For example a survey could be done on a group of people and their consumption of cabbage and the reaction of the cabbage in their digestive system (the amount of gas that could be produced) .

These experiments also raise and answer some questions. The question of why are you not supposed to use fresh pineapple in jello was answered. And a question raised is: What other fruits contain this enzyme that breaks down protein? Another question is: Would it help to eat more pineapple in order to digest the proteins in our diet?


"Enzyme". Academic American Encyclopedia. Danbury: Grolier Inc. 1995.

"Enzymes". Collier's Encyclopedia. Ed. Lauren S. Bahr and Bernard Johnston. 24vols. New York: Macmillan Educational Company, 1992.