Enzyme Activity and Environmental Factors

Impacts on Enzyme Activity

• Enzymes are proteins, and their functions are sensitive to their environments.
• Factors affecting enzyme activity:
  • Temperature
  • pH
  • Other chemicals

Effect of Temperature on Enzymes

• Increasing the temperature of a system generally increases the reaction rate.
• This is because substrates move faster and collide more frequently with the active sites of enzymes.
• This is true only up to a specific temperature, the optimal temperature, which is unique to each type of enzyme.
• Beyond the optimal temperature, the enzyme begins to denature, or lose its shape.
• This changes the shape of the active site and reduces or eliminates its function.

Optimal Temperature and Fever

• Fever: Elevation of body temperature above normal (in humans, $37.2^{\circ} C$).
• Typically, fevers develop in response to bacterial or viral infection.
• The optimal temperature for most bacterial enzymes is less than $37^{\circ} C$.
• By raising body temperature above that, the immune system attempts to denature the bacteria's enzymes and stop the infection.

Common Enzymes

• Laundry detergents contain enzymes that help break up and remove stains.
• You might want to use a different laundry detergent when you wash clothes in hot water instead of in cold water.

Effect of pH on Enzymes

• pH: A measure of the extent to which something is acidic or basic, with 7 being neutral.
• Most biological solutions have pH values between 6-8.
• pH levels that vary from the optimal for a particular enzyme can also cause it to become denatured.
• The optimal pH for most enzymes is between 6–8, but the optimal pH is different for each type of enzyme.
• Example: Enzyme with optimal pH = 4.2