High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of
A) competitive inhibition.
B) allosteric regulation.
C) the specificity of enzymes for their substrates.
D) an enzyme requiring a cofactor.
E) positive feedback regulation.

Question

Quizplus · Accepted Answer

This is an example of allosteric regulation where citric acid binds to a different location on the enzyme and changes its shape, inhibiting its activity. Competitive inhibition would involve a molecule binding to the active site of the enzyme, and the specificity of enzymes for their substrates refers to the fact that enzymes are selective in their binding to specific substrates. An enzyme requiring a cofactor would involve a molecule that is necessary for the enzyme to function properly, and positive feedback regulation involves a product of a reaction stimulating its own production.

High Levels of Citric Acid Inhibit the Enzyme Phosphofructokinase, a Key