Question

What are the factors affecting the rate of enzyme reaction?

Answer 1

1. Temperature: Heating increases molecular motion. Thus the molecules of the substrate and enzyme move more quickly resulting in a greater probability of occurrence of the reaction. The temperature that promotes maximum activity is referred to as optimum temperature.
   
2. pH: The optimum pH is that at which the maximum rate of reaction occurs. Thus the pH change leads to an alteration of enzyme shape, including the active site. If extremes of pH are encountered by an enzyme, then it will be denatured.
   
3. Substrate Concentration: For a given enzyme concentration, the rate of an enzyme reaction increases with increasing substrate concentration.
4. Enzyme Concentration: The rate of reaction is directly proportional to the enzyme concentration.
   
   Rate of enzyme reaction
   The Michaelis – Menton Constant (Km) and Its Significance:
   When the initial rate of reaction of an enzyme is measured over a range of substrate concentrations (with a fixed amount of enzyme) and the results are plotted on a graph. With increasing substrate concentration, the velocity increases – rapidly at lower substrate concentrations. However, the rate increases progressively, above a certain concentration of the substrate the curve flattened out. No further increase in rate occurs. This shows that the enzyme is working at maximum velocity at this point. On the graph, this point of maximum velocity is shown as V_Max.