Hey guys hopefully THIS post is my last on enzymes before we are able to move on to glycolysis 🙂
The following graphs show the effect of substrate concentration, enzyme concentration, and different inhibitors acting upon the enzyme.
Figure 1: Effect of Substrate Concentration on Enzymatic activity
As seen in figure 1, the rate of reaction increases with substrate concentration as more substrate becomes available to be converted into products until it begins to level off at Vmax, where Vmax refers to the maximum velocity for the reaction to occur. This leveling off occurs when the substrate saturation occurs and all active sites of the enzymes are continuously being used to catalyze the reaction.
Figure 2: Effect of Enzyme Concentration on Enzymatic Activity
Figure 2 displays the effect of enzyme concentration on the reaction rate. It can be seen that an increase in enzyme concentration increases the rate of reaction since there are more available active sites for the reaction to proceed resulting In an increase in reaction rate.
Figure 3: Effect of Competitive Inhibition on Enzyme Activity
Competitive inhibition, shown in figure 3, occurs when the inhibitor competes with the substrate for the active site, binding preventing the reaction to be catalyzed. Thus this causes a decrease in Vmax and a subsequent increase in km as the affinity for the substrate to bind to the active site decreases.
Figure 4: Effect of Non-Competitive inhibition on Enzyme Activity
Non-Competitive inhibition, figure 4, is as a result of the inhibitor binding to a site other than the active site on the enzyme, referred to as the allosteric site, changing the shape of the active site, preventing the reaction from proceeding. This therefore causes a reduction in Vmax. The affinity of the enzyme to bind to the substrate however remains the same, therefore km does not change.
Figure 5: Effect of Un-Competitive inhibition on Enzyme Activity
Figure 5, displaying Un-competitive inhibtion shows a decrease in Vmax and a reduction in km. This is because inhibitors bind to the enzyme substrate complex preventing the final product from being formed, reducing the rate of reaction (and subsequent Vmax). Km decreases since the affinity for the substrate to bind to the complex increases since the inhibitor binds to the enzyme after it has binded to the substrate, it does not therefore reduce the ability of the substrate to bind to the active site.