What will happen to the enzyme activity if both competetive and non-competetive inhibitors appear at the same time together with substrates in a reaction? Which inhibitor will affect the rate of the reaction in more?
To understand the effects of both competitive and non-competitive inhibitors on enzyme activity, let's first discuss what each type of inhibitor does.
1. Competitive inhibitors: These inhibitors compete with the substrate for the active site of the enzyme. They bind reversibly to the active site and prevent the substrate from binding. Increasing the concentration of the substrate can overcome the inhibitory effect of a competitive inhibitor.
2. Non-competitive inhibitors: Unlike competitive inhibitors, non-competitive inhibitors bind to a site on the enzyme other than the active site, known as an allosteric site. This binding causes a conformational change in the enzyme, which reduces its activity regardless of the substrate concentration. Increasing the substrate concentration does not reverse the inhibitory effect of a non-competitive inhibitor.
Now, when both competitive and non-competitive inhibitors are present simultaneously with substrates in a reaction, several scenarios can occur:
1. If the competitive inhibitor binds to the active site of the enzyme, it will directly compete with the substrate. This will reduce the rate of the reaction as long as the concentration of the competitive inhibitor is significant enough to significantly obstruct the substrate from binding to the active site.
2. If the non-competitive inhibitor binds to the allosteric site of the enzyme, it will cause a conformational change in the enzyme's structure, rendering it less effective even if the substrate is present in sufficient quantity. Non-competitive inhibitors reduce the maximum rate of the reaction, but they do not affect the substrate's ability to bind to the active site.
The impact of each inhibitor on the rate of the reaction depends on their respective concentrations. If the competitive inhibitor concentration is significantly higher than the non-competitive inhibitor, it will have a greater effect on reducing the rate of the reaction because it directly blocks the active site. However, if the concentration of the non-competitive inhibitor is significantly higher, it will have a more pronounced impact as it affects the enzyme's overall activity by altering its structure.
In summary, the relative effect of the competitive and non-competitive inhibitors on enzyme activity depends on their concentrations. The inhibitor with the higher concentration will have a greater impact on reducing the rate of the reaction.