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 what will happen to enzyme activity in the presence of both competitive and non-competitive inhibitors, we need to consider their mechanisms of action.
Competitive inhibitors: These inhibitors compete with the substrate for binding to the active site of the enzyme. They directly interfere with the formation of enzyme-substrate complexes.
Non-competitive inhibitors: These inhibitors bind to a distinct site on the enzyme called the allosteric site. Binding of the non-competitive inhibitor alters the shape of the active site, making it less effective at converting substrate to product.
When both competitive and non-competitive inhibitors are present along with the substrates in a reaction, both inhibitors can interact with the enzyme, affecting its activity. However, each inhibitor will have a different impact on the rate of the reaction.
The competitive inhibitor will primarily affect the rate of the reaction. Since competitive inhibitors compete with the substrate for binding to the active site, increasing the concentration of the competitive inhibitor will reduce the effective concentration of the substrate that can bind to the enzyme. As a result, the rate of the reaction will decrease as more competitive inhibitor is added.
On the other hand, the non-competitive inhibitor will also affect the rate of the reaction, but to a lesser extent compared to the competitive inhibitor. Non-competitive inhibitors bind to the allosteric site, inducing a conformational change in the enzyme's active site. This change reduces the catalytic activity of the enzyme, lowering the reaction rate. However, since non-competitive inhibitors do not compete with the substrate for binding, their presence does not directly reduce the effective concentration of the substrate. Hence, the impact on the reaction rate is generally less pronounced compared to competitive inhibitors.
In summary, when both competitive and non-competitive inhibitors are present together with substrates in an enzymatic reaction, the competitive inhibitor will have a greater effect on reducing the reaction rate, while the non-competitive inhibitor will have a relatively smaller effect.