Question

Malonate is a competitive inhibitor of succinate dehydrogenase. If malonate is added to a mitochondrial preparation that is oxidizing pyruvate as a substrate, which of the following compounds would you expect to initially decrease in concentration?A) Citrate

B) Fumarate
C) Isocitrate
D) Pyruvate
E) Succinate

Answer 1

B) is the correct option

Step-by-step explanation:

• Succinate dehydrogenase is the smallest component of electron transport chain and consists of four different subunits including FAD, 3 Fe-S centers
• It catalyzes oxidation of succinate to fumarate and electrons released transferred to ubiquinone
• Succinate dehydogenase transfer electrons from succinate to ubiquinone via FADH2 thus this complex directly links tricarboxylic acid cycle to electron transport chain
• Activity of succinate dehydrogenase is inhibited by malonate which is a competitive inhibitor as a result oxidation of succinate to fumarate will not occur and hence concentration of fumarate will decrease