Question

Experiment IV: Effect of pH on the Rate of Enzyme Reaction

5. Why does pH have this effect?

Answer 1

A pH is defined as the measure of the concentration of hydrogen ions. The tertiary structure of enzymes are stabilized by various ionic, electrostatic and hydrogen bonds. When there is a change in pH, there will be a change in the concentration of hydrogen ions. This change can alter the shape and charge of enzyme as well as of substrate due to which  the substrate cannot bind properly to the active site of an enzyme (according to induced-fit model, proper binding or interaction of substrate on the active site of enzyme is necessary for the reaction to catalyze) and enzyme-substrate complex would not be able to formed and therefore enzyme would not catalyze the reaction. So, increasing or decreasing the pH may alter the rate of enzyme reaction.