Factors Effect on Enzyme Activity

Suzanna Stenger, 6th Period, Allen High School


Enzymes are proteins that act as catalysts in reactions throughout living organisms. They are extremely efficient, but can react negatively to certain exterior parameters. If the environment an enzyme is in is too basic or too acidic the enzyme may react negatively and denature until it can no longer catalyze the reaction. The enzyme Catalase aids in breaking down hydrogen peroxide (toxic to most organisms) into water and oxygen gas.

Research Question:

How do various pH levels affect the enzyme activity of Catalase?


Explanatory Hypothesis: Catalase will react more efficiently in the environment with a pH of 7.

Prediction: As the pH increases, enzyme activity will increase until it reaches its optimum pH, after which activity will decrease.

Null Hypothesis: None of the pH values will be the optimum environment for Catalase.

Alternative Hypothesis: One of the pH values will be the optimum value for Catalase.


The environment with a pH of 7 will be the optimum for activity; at 10 pH Catalase will begin to denature.


Each test tube had an amount of buffer, hydrogen peroxide (the substrate), and varying pH levels added. Enzyme solution was added. The test tube was then swirled and an air pressure probe was added. Data of the changing air pressure was logged for 3 minutes after which the probe was removed and another trial began.
Big image


The data is nearly linear, meaning the rate of enzyme activity was nearly constant. All of the pH environments resulted in a positive rate or activity.


According to the data, none of the pH environments provided the optimum rate of activity. In addition, the data shows that 10 pH had the highest rate of activity, which shouldn't be true. Human error occurred meaning that the data is flawed, either the probe was placed incorrectly or the mixture in the test tube was not thoroughly mixed.