In a reaction catalyzed by a dehydrogenase, it was observed that NAD⁺ was required for binding of the second substrate. The reduced form of NAD was found to be a competitive inhibitor against NAD⁺. Which of the mechanisms listed below describes the action of this enzyme? A) Random B) Ordered sequential C) Ping Pong D) Concerted E) None of the above

Question

Quizplus · Accepted Answer

The requirement of NAD⁺ for binding of the second substrate suggests that the enzyme follows an ordered sequential mechanism, where the substrates bind to the enzyme in a specific order. The competitive inhibition of the reduced form of NAD against NAD⁺ indicates that NADH competes with the first substrate for binding to the enzyme, confirming the ordered mechanism.

In a Reaction Catalyzed by a Dehydrogenase, It Was Observed