Factors Affecting the Rate of Enzyme Action:

1. Temperature:

Temperature increases will speed up the rate of enzyme-catalyzed reactions, but only to a certain limit.

Optimum Temperature:

Every enzyme works at its maximum rate at a specific temperature called the optimum temperature for that enzyme. When the temperature rises to a certain limit, the heat adds in the activation energy and also provides kinetic energy and so reactions are accelerated.

Denaturation of Enzyme:

When the temperature is raised well above the optimum temperature, the heat energy increases the vibrations of atoms of enzyme molecules and the globular structure of the enzyme is lost. This is known as the denaturation of the enzyme. It results in a rapid decrease in the rate of enzyme action and it may be blocked completely

1. Substrate concentration:

If there are enzyme molecules with vacant active sites, an increase in substrate concentration will increase the rate of reaction. If the enzyme concentration is kept constant and the amount of substrate is increased, a point is reached where any further increase in substrate does not increase the rate of reaction anymore. When all the active sites of the enzymes are occupied (at high substrate concentration) any more substrate molecules do not find free active sites. This state is called saturation of active sites and the reaction rate does not increase.

1. pH:

All enzymes work at their maximum rate at a narrow range of pH, called the optimum pH. A slight change (increase or decrease) in this pH causes retardation in enzyme activity or blocks it completely. Every enzyme has its specific optimum pH value. For example, Pepsin (working in the stomach) is active in an acidic medium (low pH) while trypsin (working in the small intestine) shows its activity in an alkaline medium (high pH) Change in pH can affect the ionization of the amino acids at the active site.