Temperature
Increasing the temperature means that the particles have more kinetic energy – this increases the rate of reaction.
However, there are limitations as at the maximum temperature, the hydrogen bonds break. The rate of reaction decreases as the shape of the active site has changed. Therefore, the enzyme cannot catalyse the specific biological reaction – this is because they have denatured.
pH
All enzymes have an optimum pH they can work at. This is because the ionic and hydrogen bonds are affected by the presence and absence of H+ or OH–
If the pH is not within the optimum range, the enzymes can denature.