Question

Noncompetitive inhibition within a metabolic pathway prevents excess accumulation of the pathway's product. This occurs when the product binds the active site of an enzyme, reducing its activity, and the subsequent accumulation of product. What is the mechanism of noncompetitive inhibition?

1) The product binds to the allosteric site of the enzyme, causing a conformational change that reduces the enzyme's activity.
2) The product competes with the substrate for the active site of the enzyme, reducing the enzyme's activity.
3) The product binds to the active site of the enzyme, preventing the substrate from binding and reducing the enzyme's activity.
4) The product binds to a coenzyme required for the enzyme's activity, inhibiting the enzyme's function.

Answer 1

Noncompetitive inhibition occurs when a product binds to the allosteric site of an enzyme, causing a conformational change that reduces its ability to catalyze reactions by altering the active site's structure.

Step-by-step explanation:

The mechanism of noncompetitive inhibition involves the product binding to the allosteric site of an enzyme, which is different from the active site. This binding induces a conformational change in the enzyme, altering the structure of the active site and reducing its activity. Unlike competitive inhibition where the inhibitor competes with the substrate at the active site, in noncompetitive inhibition, the inhibitor can bind to the enzyme whether or not the substrate is bound, effectively decreasing the enzyme's affinity for the substrate and preventing the formation of a product. This regulatory mechanism is important in metabolic pathways, such as the catabolism of carbohydrates, to prevent excess accumulation of end products.