The activity of enzymes is strongly affected by changes in PH and temperature. Each enzyme works best at a certain PH and temperature. Its activity decreasing at values above and below that point. This is because of the importance of tertiary structure ( i.e shape) in enzyme function and forces.
Example – Ionic interactions and hydrogen bonds in determining that shape.
Temperature : enzyme work best at an optimum temperature.
Below this, an increase in temperature provides more kinetic energy to the molecules involved. The number of collisions between enzyme and substrate will increase so the rate will too.
Above the optimum temperature, and the enzymes are denatured. Bonds holding the structure together will be broken and the active site loses its shape and will no longer work.
PH enzymes have an optimum PH. If the PH changes much from the optimum, the chemical nature of the amino acids can change.
This may result in a change in the bonds and so the tertiary structure may break down. The active site will be disrupted and the enzyme will be denatured.