Factors Affecting Enzymic Reactions

Factors affecting the rate of Enzymic Reactions

Enzyme concentration:-

The rate of an enzymatically-controlled reaction is directly proportional to the enzyme concentration under constant conditions if an excess of free substrate molecule is present. As the concentration of the enzyme increases, the rate of reaction will also increase.Thus, enzyme –substrate interaction follow the mass-action law.

Substrate concentration:-

The rate of reaction is slow at very low concentration of substrate, but increases with the increase in substrate concentration up to certain concentration, where there is no increase in enzyme activity with the increase in substrate concentration. Eventually, a maximum is reached, and further addition of substrate has

All enzymes have a characteristic pH at which their activity is maximum. At pH lower or higher than the optimal pH, the activity of an enzyme decreases. The optimum pH of the enzyme is not necessary identical with the pH of its normal surroundings. With few exceptions, most of the enzymes have their optimal activity between pH 5-9. Pepsin is the typical example of the enzyme, which functions in acidic range and has maximal activity at about pH 2, and the optimal activity of trypsin is in alkaline range. The pH dependence of enzyme activity is the consequence of several effects. The optimum pH of the enzyme depends upon the protonating and proton accepting groups in the active site of the enzyme, in the substrate, or in the enzyme-substrate complex can affect catalysis depending on whether the protons on the reactive groups are dissociated or undissociated. Ionization of these groups depends on different factors such as pK values, the chemical properties of surrounding groups, and the pH of the reaction medium. Changes in pH affect the binding of the substrate at the active site of the enzyme and also the rate of breakdown of the enzyme-substrate complex. These can also be the change in conformation of enzyme at extreme