Question

You add an uncompetitive inhibitor to your enzyme assay.

What will happen to K_m' and V_max ',   relative to K_m and V_max? Choose all correct answers.

Group of answer choices

Vmax' is higher

Vmax' is the same

Km' is higher

Vmax' is lower

Km' is lower

Km' is the same

Answer 1

Uncompetitive inhibitors binds to the ES complex. These inhibitors leads to a  decrease in Km ( Km gives the concentration of substrate at which the Vmax or maximum velocity is half , that is if Km is low then the substrate has more affinity for the enzyme and if Km is towards high end then substrate affinity for enzyme reduces )  . This happens because of increased binding efficiency and binding to the enzyme-substrate complex, uncompetitive inhibitors pull that complex out from the reactions. This removal of substrate causes decrease in its concentration, allowing the enzyme free to perform. However uncompetitive inhibitors decrease Vmax by interfering with substrate binding and reduces or hampers catalysis in the ES complex.

Thus correct answers would be Vmax is lower and Km is lower.

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