The Effect of pH on Enzyme Reaction Rate, Why the enzyme reaction rate decreases upon decreasing and increasing the pH of the enzyme’s environment from the optimum pH?

The Effect of pH on Enzyme Reaction Rate

Enzymes are proteins that are critical for life and are responsible for biochemical reactions. They are highly sensitive to pH, and the rate of an enzyme reaction is affected by changing the pH of its environment. The optimum pH of an enzyme is the pH at which the enzyme works the best, and the rate of reaction is highest. If the pH of the environment is lower or higher than the optimum pH, then the enzyme reaction rate will decrease. The activity of an enzyme is affected by pH because the shape of the enzyme’s active site is altered. At a pH below the optimum pH, the active site of the enzyme may become more positively charged and repel the substrate molecules, reducing the rate of reaction. Conversely, at a pH higher than optimum, the active site may become more negatively charged and again repel the substrate molecules, also reducing the rate of reaction. This phenomenon was discovered by the Nobel Prize-winning chemist, Christian Anfinsen, who studied enzymes in the 1950s (Anfinsen, 1957). Since then, the effects of pH on enzymes have been studied extensively (Chin et al., 2016). For example, research by Fandino and Garcia (2020) showed that altering the pH of the environment can modulate the activity of an enzyme by changing its structure and, as a result, its catalytic activity. Cont…