Catecholase Enzyme Lab
How Enzymes Work
Each enzyme has a unique shape, including a active site, which fits its target substrate much like a key
fits in a lock. If other substances that don’t fit the substrate enter the active site no reaction will occur.
How to Prevent Fruits & Vegetables From Browning
Catecholase is an enzyme present in most fruits and vegetables. It helps speed the browning of cut or
bruised produce by catalyzing a reaction between the molecule catechol and oxygen in the air. This
color change can be seen in produce such as apples and potatoes.
There are a few ways to prevent this enzymatic reaction. One is to submerge the fruit or vegetable in
water. Water doesn’t affect the enzyme catecholase, but does reduce the availability of oxygen, a
reactant required for the formation of polyphenol. This is why putting cut fresh potatoes in water
delays browning.
Enzyme Catecholase Experiment Using Apples
This experiment is so simple that it can be done in any classroom, and requires no special scientific
equipment. The supplies for each student include one of each of the following:
 apple
 lemon wedge
 paper plate
 napkin
 Have each student take a bite of their apple, and then immediately rub juice from the lemon
over the exposed flesh. Be careful not to let the juice touch other areas of the apple.
 Each student then takes another bite, on the opposite side of the apple. Do not put any lemon
juice on this area.
Questions:
After 5 minutes:
What color is the side of the apple with the lemon juice?________________________________
What color is the side of the apple without the lemon juice?_____________________________
Which side was the enzyme allowed to connect with its active site and fit into its substrate? How do
you know this?
_________________________________________________________________________________