specific enzymes have specific substrate for their action. Their affinities for
that particular substrate can be changed by different influencing factors .
Factors that affect enzyme activity are:
1. Enzyme concentration- If the amount of substrate is more than the enzyme then the enzyme activity will be decreases. On the other side if the enzyme concentration is less than the substrate concentration then the affinity for the enzyme can be increased by increasing the substrate concentration. If the K m is less then, less amount of substrate is required for the reaction.
2. Substrate Concentration-
Enzyme and substrate bindings are like lock and key model. Where enzyme is the appropriate lock and substrate is the key for the lock. If the enzyme concentration is high and the amount of substrate is less than the enzyme then the speed of formation of enzyme substrate complex concentration will be less. Then the substrate concentration should be decreases. Comparatively small K m means small afginity of substrate is required for the high velocity of the enzyme.
3. Product Concentration- Some enzyme when binds
with the substrate and produces products the concentration of the product also
influence the binding of substrate to the enzyme.
4. Temperature of the Reaction- Enzyme acts on specific range of temperature. Every enzyme has its specific temperature for highest activity and is called optimum temperature. Within the range it has been observed that enzyme activity has increased many times. But after certain increase of temperature it has been observed that the enzyme get denatured. Maximum metabolic enzyme of the animals are denatured above 40℃. It has been checked ,due to increase of 10℃ it is seen that the enzyme activity has been increased by 50-60% . Example- Optimum temperature of the maximum digestive enzymes in our body is 37℃ , according to our own body temperature. Enzymes activity decreases due to decrease of temperature.
5. pH of the Surroundings- Activity of enzymes are dependent on the specific range of pH. It varies from enzyme to enzyme. The particular pH ,where the enzyme activity is highest is called optimum pH. Due to change of pH ,enzyme activity increase or decrease. Example- peptic enzymes (pH 2) are act on acidic medium whereas pancreatic enzymes(pH 7.6) act on alkali medium.
6. Inhibitor - Inhibitor are substances that competes with the substrate. Enzyme and substrate are same like lock and key means there is specific key for specific lock. As Inhibitors act as key and it competes with the substrate to occupy the active site of the enzyme. If the Inhibitors occupy the site then the substrate cannot bind with the enzyme. As a result there is no enzyme substrate complex and no enzyme activity. Example- ribonuclease Inhibitors inhibits the activity of ribonuclease and causes inhibition of protein – protein interactions.
7. Inducer- Sometimes some activity of the enzyme may change due to activity of the inducer. Inducer binds with the enzyme first and the complex which formed has high affinities for the substrate bindings.Example- Aminoglutethimide is an inducer that increase enzyme activity.