The enzyme amylase is present in saliva, plant leaves, and plant seeds. Its job is to break down starches into usable energy. In humans and animals, starches in foods are broken down before leaving the mouth to make them easier to digest. In plant leaves, amylase breaks down nutrients that have been converted to starch by photosynthesis. Seeds often contain very high amounts of amylase because seeds require so much energy during germination. Amylase experiments involve exposing the enzyme to different temperatures and experimenting with seeds to see which ones contain the highest amount of amylase.
Though amylase functions easily in the warm mouths of animals and humans, this function may be slowed by extreme heat or cold. To see just how much heat or cold the enzyme can take, scientists can sprinkle an amylase solution over starchy foods and expose them to different temperatures. The food may be white rice, torn bits of white bread, crackers, or even cornmeal. The scientist generally distributes the starchy food among four different test tubes. A few drops of amylase solution are added to each test tube.
The scientist then fills three beakers half-full with water. He or she places one beaker over a heat source, bringing the water to a boil. A second beaker goes into the refrigerator to be chilled for an hour or two. The third water-filled beaker is left at room temperature, while a fourth beaker remains empty. When all the beakers are prepared, the scientist gently places a test tube into each and waits up to 15 minutes.
When the time is up, the scientist drips a little iodine into each test tube and waits about three minutes. If the starchy food turns purple, it means the amylase has not converted the starches in the food because iodine only turns starches purple. If the food remains white, the amylase has done its work. Most amylase experiments reveal that the cold and boiling water slow the function of the amylase. If the scientist checks on the purple food after 20 more minutes, it may be turning white again. This means the amylase is beginning to function again as it returns to a median temperature.
Some tests reveal how long seeds hold onto their amylase. These amylase experiments require the scientist to obtain starch-agar petri dishes and some starchy seeds, like corn kernels. One quarter of the kernels should be extremely fresh, while another quarter should be freshly dried. The third quarter should be kept warm for a week to help them germinate, while the fourth and last quarter should be dried and at least a year old.
To perform the experiment, the scientist cuts up to 10 seeds from each category in half and places each type in its own petri dish. The seeds should be spaced about 1 inch (2 cm) apart. The dishes should be capped overnight. The next morning, the scientist removes the seeds from the dishes and floods them iodine.
After rinsing the plates in cool water, the scientist can see which plates have turned purple and which plates are clear. Purple color indicates the amylase is inactive, while clear plates indicate the amylase is present and functioning. The fresh and partially germinated seeds often show the highest amounts of amylase, though some dried and older seeds may still contain high quantities, as well. Amylase experiments like this may need to be repeated to obtain viable results.