Rate of Enzyme Action
Biology: Cambridge International GCSE Supplement, topic 5.1.2
Factors Affecting the Rate of Enzyme Action
The factors that affect the rate (speed) of enzyme action are:
Temperature
- Increasing the temperature of a working enzyme initially increases the reacting activity. Molecules have more kinetic energy, so there are more frequent collisions (meetings) between substrates and enzymes.
- Enzymes have an optimum temperature. Once this temperature is reached, the activity decreases.
- Past a certain temperature, the active site changes shape, and the enzyme is denatured (loses its catalytic activity).
pH (measure of acidity)
- Enzymes have an optimum pH (measure of acidity).
- If the pH changes away from the optimum pH, then the enzyme activity decreases.
- If the pH is too low or too high, then the enzyme is denatured and will not function.
Test yourself on Rate of Enzyme Action
What happens to enzymes when pH is very high?