You have an enzyme, its substrate, and a small molecule. If you perform a reacti

Question

You have an enzyme, its substrate, and a small molecule. If you perform a reaction with the enzyme and substrate, you can detect lots of product after 5 minutes. If you perform a second reaction with all three, you fail to detect product even after 30 minutes. When you further analyze your second reaction, you determine that the substrate is bound to the enzyme. Why is no product produced when the substrate can bind the enzyme?

The small molecule is an enzyme cofactor.

The small molecule is a competitive inhibitor of the enzyme.

The small molecule is a noncompetitive inhibitor of the enzyme.

The small molecule changes the G of the reaction.

The small molecule is an enzyme cofactor.

The small molecule is a competitive inhibitor of the enzyme.

The small molecule is a noncompetitive inhibitor of the enzyme.

The small molecule changes the G of the reaction.

Explanation / Answer

The correct answer is 'C' i.e. The small molecule is a non-competitive inhibitor of the enzyme.

In case of non-comptitive inhibition, the inhibitor binds to the enzyme and decreases its activity. The effect of inhibition depends on the inhibitor concentration. It does not affect the binding, hence Km remains same and have proper function. In this, the inhibition leads to the inability to proceed the reaction and does not form the product. Vmax reduces in this type of inhibition.

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