U3 AOS1 Topic 7: Factors Affecting Enzyme Function

Factors that can affect enzyme function include

1.     Temperature

2.     pH

3.     Concentration

4.     Enzyme inhibitors

 

1.   Temperature:

Enzymes work at optimum temperature. Optimum temperature is the point at which enzyme’s activity is greatest.  Change in this temperature affects the enzyme activity.

·        Enzyme activity when temperature increases:

Enzymes are proteins in nature and when the temperature exceeds the optimum temperature of an enzyme, the enzyme is denatured causing a conformational change in enzyme. The bonds in enzymes are broken due to heat and therefore the correct folding or shape of enzyme is lost and can never be retained. Due to which the substrate can no longer bind to the active site of enzyme.

·        Enzyme activity when temperature decreases:

Decrease in temperature does not cause permanent conformational change of enzyme but slows the enzyme activity. When temperature decreases, the enzyme and substrate do not have enough kinetic energy to move and collide frequently therefore enzymes show no activity.

2.   pH:

Enzymes have optimum pH at which their activity is highest. Enzymes can denature when pH is too acidic or too basic for that enzyme. The pH range at which a specific enzyme works depends on the location for example, pepsin is a digestive enzyme secreted in stomach and its optimum pH is 1.5-2 so that it can function in an acidic environment whereas pancreatic lipase has an optimum pH 8.

3.   Concentration:

Concentration of both substrate and enzyme affects the enzyme activity.

·        Concentration of substrate:

When the substrate concentration increases and the enzyme concentration remain constant, the rate of reaction increases until it reaches the saturation point where all of the enzymes active sites are occupied by the substrate and no more substrate can bind to the enzymes.

·        Concentration of enzyme:

When the enzyme concentration increases and the substrate concentration remain constant, the rate of reaction increases until there is no more substrate available for enzyme.

4.   Enzyme inhibitors:

Enzyme activity can be affected by the presence of enzyme inhibitors. When an inhibitor binds to the enzyme, the enzyme can no longer function. Inhibitor can be competitive and non competitive. Competitive inhibitors bind to the active site of an enzyme so that substrate cannot bind whereas, non competitive inhibitors bind to the site other than active site called as allosteric site and cause conformational change in the enzyme’s active site so that substrate can no longer bind to active site.