Effect of pH on enzyme activity
pH is a measure of how acidic or alkaline a solution is.
Description
Enzyme activity is at its maximum value at the optimum pH. As the pH value is increased above or decreased below the The best or most appropriate - for instance, the conditions under which an enzyme works best (eg temperature and pH). pH the enzyme activity decreases.
Explanation
At very acidic and alkaline pH values the shape of the enzyme is altered so that it is no longer complementary to its Refers to the fact that each enzyme will only act on one particular substrate. substrate. This effect can be permanent and irreversible and is called denaturation.
The diagram below shows what happens to an enzyme when denaturation occurs.
Each enzyme has an optimum pH but it also has a working range of pH values at which it will still work well. This depends on the type of enzyme.
The enzyme pepsin breaks down proteins in the acidic conditions of the stomach. Pepsin has an optimum of pH 2.5 and a working range of between pH 1-4. Catalase has an optimum pH of 9 and a working range of between pH 7-11. Most other enzymes function within a working pH range of about pH 5-9 with neutral pH 7 being the optimum.