- What is the optimal pH for catalase? Why do you think it becomes less effective at high or low pH?
- Can you think of anywhere in the human body where enzymes would work BEST at a high PH? Please give an example and draw what that graph might look like.
- What is the optimal temperature for catalase? Why do you think it becomes less effective at high or low temperatures?
- What is the optimal pH for
- Can you think of any organisms that would have enzymes specifically adapted to extreme low or high temperatures and would therefore function best at a different part of the graph? Please give an example and draw what that graph might look like.
The Correct Answer and Explanation is :
19. Optimal pH for Catalase
The optimal pH for catalase is around pH 7, which is neutral. Catalase is an enzyme that helps break down hydrogen peroxide into water and oxygen, and its activity is most efficient at neutral pH. At low pH (acidic) or high pH (alkaline), the enzyme’s structure can be altered, affecting the active site where the reaction takes place. Changes in pH can lead to the denaturation of the enzyme, causing it to lose its shape and thus its functionality. In acidic conditions, hydrogen ions can interfere with the enzyme’s structure, while in alkaline conditions, hydroxide ions can have a similar effect.
20. Enzymes That Work Best at High pH in the Human Body
An example of an enzyme that works best at a high pH is pepsin. Pepsin is a digestive enzyme found in the stomach that operates most effectively in a highly acidic environment, but if we consider alkaline enzymes that work best at high pH, we could look at intestinal enzymes like pancreatic amylase, which helps break down carbohydrates in the small intestine. The optimal pH for pancreatic amylase is around pH 8, which is slightly alkaline. The enzyme’s activity is slower in an acidic environment due to the changes in its structure.
Graph Explanation: For pancreatic amylase, the activity would start to rise as the pH increases from acidic to neutral and then peak at around pH 8, where it is most efficient. The enzyme’s activity would decline as the pH increases further into more alkaline conditions (e.g., pH 10), as the enzyme may begin to denature.
21. Optimal Temperature for Catalase
The optimal temperature for catalase is around 37°C (human body temperature). At this temperature, the enzyme’s activity is at its peak because the molecular collisions are most efficient at moderate temperatures. However, at very high temperatures, the enzyme can denature and lose its shape, resulting in a loss of function. At low temperatures, the enzyme’s molecules move slower, leading to reduced reaction rates because the activation energy is harder to overcome.
22. Enzymes Adapted to Extreme Temperatures
Organisms like thermophiles (heat-loving bacteria) have enzymes that are adapted to high temperatures. These enzymes are stable and functional even at temperatures above the usual optimal temperatures for most organisms. For example, Taq polymerase, used in PCR (Polymerase Chain Reaction), is derived from a thermophilic bacterium and has an optimal temperature around 75°C, much higher than the temperature at which most enzymes in the human body function. The graph for Taq polymerase would show a peak at a high temperature compared to catalase.
I’ll now generate a graph for pancreatic amylase and Taq polymerase showing their optimal pH and temperature ranges.
The graphs above illustrate the optimal pH for pancreatic amylase and the optimal temperature for Taq polymerase:
- The first graph shows the activity of pancreatic amylase peaking at pH 8, which is where it works best in the slightly alkaline environment of the small intestine. As the pH moves away from this value, the enzyme’s activity decreases.
- The second graph shows Taq polymerase, an enzyme derived from a heat-loving bacterium, with its peak activity at a much higher temperature of 75°C. This enzyme is adapted to work at extreme temperatures, making it highly effective for applications like PCR.
These graphs reflect how enzymes have optimal conditions where they work most effectively and how their activity diminishes outside those conditions.