Question

Which of the following is an example of feedback inhibition?

• A. Cyanide action on cytochrome.
• B. Sulpha drug on folic acid synthesizer bacteria.
• C. Inhibition of hexokinase by glucose-6-phosphate.
• D. Reaction between succinic dehydrogenase and succinate.

Answer 1

The correct option is C Inhibition of hexokinase by glucose-6-phosphate.

Allosteric modulation or feedback inhibition is an enzyme regulatory mechanism where a product of a simple or chain reaction can function as a temporary allosteric inhibitor, i.e., an inhibitor that combines with a regulatory or allosteric site (other than the active site) if its concentration crosses a threshold value. Example: excess of glucose-6-phosphate stops the activity of enzyme hexokinase that helps in its formation from glucose and ATP.