Discuss the factors affecting enzyme activities.

(N/A) The factors affecting enzyme activity include temperature,$pH$,changes in substrate concentration,or the binding of specific chemicals that regulate activity.
$(1)$ Temperature and $pH$: Each enzyme shows its highest activity at a particular temperature and $pH$,known as the optimum temperature and optimum $pH$.
Activity declines both below and above these optimum values.
Low temperature preserves the enzyme in a temporarily inactive state,whereas high temperature destroys enzymatic activity because proteins are denatured by heat.
$(2)$ Concentration of substrate: With an increase in substrate concentration,the velocity of the enzymatic reaction rises at first. The reaction ultimately reaches a maximum velocity $(V_{\max})$ which is not exceeded by any further rise in substrate concentration. This occurs because the enzyme molecules are fewer than the substrate molecules,and after saturation,there are no free enzyme molecules to bind with additional substrate molecules.
$(3)$ Specific chemicals: The activity of an enzyme is also sensitive to the presence of specific chemicals that bind to the enzyme.
When the binding of a chemical shuts off enzyme activity,the process is called inhibition,and the chemical is called an inhibitor.
When the inhibitor closely resembles the substrate in its molecular structure,it is known as a competitive inhibitor. Due to structural similarity,the inhibitor competes with the substrate for the substrate-binding site of the enzyme. As a result,the substrate cannot bind,and enzyme action declines. For example,the inhibition of succinic dehydrogenase by malonate,which closely resembles the succinate structure. Such competitive inhibitors are often used in the control of bacterial pathogens.