This experiment was done to observe the effects of enzymes on different substances. The enzymes tested were amylase in saliva, catalayse in cabbage, and bromelain in pineapple. This experiment observed whether heat affected the reaction of enzymes, and how pH levels affected enzymes. Each enzyme was tested against a particular substance, and the results were checked after a few days in the case of bromelain, and the same day in the cases of amylase and catalayse. The experiment showed that heat dramatically decreased the effectiveness of enzymes, and that pH did indeed effect the activity of an enzyme. It also showed that sugar did have an effect on the activity of an enzyme.



Enzymes react differently when the temperatures of certain substances are changed. What we hope to show in this experiment is that enzyme reactions can be slowed down or sped up depending upon whether the substance is heated or cooled down. This is an important experiment in that we need to know how enzymes work and also how they are affected by variations in temperature and their surroundings. This information will prove to be interesting because it is most likely that these enzymes are going to be manipulated in some form or another. It is essential to find out how and why enzymes are slowed down or not so as to do more research in medical fields of study or things of that nature. We hope to prove from this experiment that heating up a substance will cause the enzymes in it to stop working, and also if cooled down to slow down the reaction of the enzymes in that substance. With this information in mind, we hope to set up in this study: I. the effects that saliva will have on the reactions of enzymes, II. the effects that heating and cooling will have on the enzymes in egg and jello, and III. the effects that cabbage juice will have on the reactions of the enzymes.


Literature Review

In Compton's Encyclopedia enzymes are the crux of genetic engineering. There are many different ways that enzymes help in genetic engineering. Enzymes allow scientist to cut the chromosome of DNA into various desired length. Each time a particular restriction enzyme or set of restrictions enzymes is used, the DNA is cut into the same number of pieces of the same length and composition. At least 80 restriction enzymes are now known. When restriction enzymes are used along with other enzymes that tie together loose ends of DNA, it becomes possible to remove a bit of DNA from one organism's chromosome and to insert it into another organism's chromosome.

Also in Compton's Encyclopedia enzymes are referred to as a preserver. Enzymes can also help in the increasing of shelf life for fresh fruits and vegetables. In a recent experiment scientist were called upon to help out in the problem of soft tomatoes. When the tomatoes were aloud to ripen on the vine the were found to be to soft for shipping. For this reason most store bought tomatoes are picked green, refrigerated while shipped, and then treated with ethylene gas to bring on the red color. The enzyme responsible for fruit softening is polygalacturonase. Scientist have taken the polygalacturonase gene and have inserted it, in reverse orientation, into tomato plants, giving the plants two genes for the enzyme. When the two genes meet, it leads to production of messenger RNAs that are complimentary to each other. The two RNAs bind to one another and cannot be translated into the enzyme. This has a 90 percent decrease in the softening process. Under these conditions, the tomatoes are left to ripen on the vine, allowing the natural flavor to develop fully, and are then shipped without refrigeration. The production of this gene-altering tomato has changed a perishable fruit requiring an expensive refrigeration facility for shipping into a relatively sturdy fruit that can be made available to poorer populations.


Materials and Methods

There are three parts to this experiment. Each substance should be used in 5 mL increments. The first part involves the activity of the enzyme amylase in saliva. The first test tube will contain distilled water; the second a starch solution; the third a maltose solution; the fourth saliva; the fifth a combination of the starch solution and saliva. Benedict's solution will be added to each test tube. Then each test tube will be heated over the bunsen burner. The second part involves the activity of the enzyme bromelain in pineapple. 10 test tubes will be involved in this part of the experiment. In the first four test tubes will be formed jello. Fresh pineapple juice will be added to test tubes 1 and 3. Cooked pineapple juice will be added to test tubes 2 and 4. Test tubes 1 and 2 will be kept at room temperature. Test tubes 3 and 4 will be refrigerated. The other 6 test tubes will each contain formed egg white. Fresh pineapple juice will be added to test tubes 1, 3, and 5. Cooked pineapple juice will be added to test tubes 2, 4, and 6. Test tubes 1 and 2 will be kept at room temperature. Test tubes 3 and 4 will be refrigerated. Test tubes 5 and 6 will be kept in an incubator at 37 degrees celsius. All test tubes involving the pineapple juice should be checked for results after a few days. The third part of the experiment involves the activity of the enzyme catalayse in cabbage. Test tube 1 will contain distilled water; test tube 2 will contain cabbage juice; test tube 3 will contain vinegar; test tube 4 will contain an ammonia solution; test tube 5 will contain distilled water and cabbage juice; test tube 6 will contain vinegar and cabbage juice; test tube 7 will contain ammonia solution and cabbage juice. Each test tube's pH should be checked with pH paper. Then, peroxide (H2O2) will be added to each test tube to see what reaction they each have to the substance.





In part A ,the effects of amylase on starch, when saliva mixed with starch there was a reaction in both the iodine and the Benedicts solution. Therefore the enzyme in saliva turns the starch into sugar.

In part B-1, the effects of temperature on enzyme activity of Bromelain, cooking the pinneapple juice denatured the enzyme Bromelain and kept it from eating the jello. The uncooked pinneapple juice's Bromelain enzyme ate the protein in jello. Therefore, extreme heat denatured the enzyme while room temperature allowed it to work thoroughly.

In part B-2, the effects of temperature on enzyme activity of Bromelain, the same effects occurred as in B-1, but the refridgeration of the third and fourth test tubes significantly slowed down the reaction of the Bromelain enzyme in dissolving the egg white.

In part C, the effects of pH on Catalase activity, the strongest reactions occurred in the contents which had neutral pHs. Therefore the conclusion is that strong acids or bases weaken the activity of the Catalase enzyme.