CHAPTER 20: Unit 6. Factors Affecting Enzyme Activity

The factors affecting the activity of an enzyme are:

Reference: https://www.easybiologyclass.com/factors-affecting-enzymatic-activity-biochemistry-lecture-notes/

1. Temperature
2. Water Presence
3. pH
4. Substrate Concentrations
5. Enzyme Concentrations
6. End Products Accumulations
7. Activators
8. Inhibitors
9. Radiation and Light

Reference: https://www.easybiologyclass.com/factors-affecting-enzymatic-activity-biochemistry-lecture-notes/

1.  Temperature:The enzyme activity decreases at very low temperature and its increase with increasing temperature till it reaches the optimum temperature (at the maximum of the graph).With very higher temperatures above the optimum temperature, the enzyme starts to denature and decompose.In general, the optimum temperature for maximum activity can be in the range of 30oC – 45oC.

Reference: https://www.rsc.org/Education/Teachers/Resources/cfb/enzymes.htm

2. Water PresenceWater presence is very important for the enzyme activity. Without water, the enzyme becomes inactive. Sometimes water is considered as one of the reactants.

3. pHThe pH by which the enzyme can exhibit optimum activity has an optimum value.Each enzyme exhibits maximum activity at specified pH

Reference: https://www.rsc.org/Education/Teachers/Resources/cfb/enzymes.htm

4. Substrate ConcentrationsIncreasing the substrate concentration will increase the enzyme activity. This will continue till the substrate concentration saturating all the active sites of the enzyme.After the saturation of all active sites of the enzyme, the enzyme activity will not change, and it becomes steady.At a higher concentration of substrate, the effect of competitive inhibitors will be decreased.

Reference: https://www.rsc.org/Education/Teachers/Resources/cfb/enzymes.htm

5. Enzyme ConcentrationsIncreasing the concentrations of the enzyme will increase the enzyme activity (enzyme increases the rate of reaction), thus increasing the number of active centers. At higher concentration of enzyme, the effect ofinhibitors will be decreased.

6. End Products AccumulationsEnd products accumulations will inhibit the enzyme activity. The active sites will be very crowded and blocked by the accumulation of the end products.Inhibition by end product accumulations is considered as a regulation mechanism of the enzyme such as Feed Back Inhibition or Allosteric Modulation.

7. ActivatorsSome enzymes need specific prosthetic groups (also called co – factors) to exhibit maximum activity. Such prostatic groups can be K+, Na+, Ca2+, Cu2+, Mg2+ etc.

8. InhibitorsInhibitors inhibit the enzymes’ activity. The inhibition is specific, and it is depending on the inhibitor type and nature. Inhibitors are less effective at higher concentrations of the substrate and enzyme.There are three types of inhibitors:Competitive inhibitorsNoncompetitive inhibitorsUncompetitive inhibitors

9. Radiation and LightLight can be very important to some enzymes to function properly (photolyase enzyme which requires light for the photoreactivation of DNA repair).X – rays, UV rays, alpha, beta and gamma radiations can cause an enzyme oxidation and peroxides are formed which decrease the enzyme activity due to oxidation.

The videos below illustrate the factor affecting the activity of the enzymes: