Question

Which of the following is an inhibitor of the complex IV of ETC?

• A. Rotenone
• B. Amobarbital
• C. Antimycin A
• D. Carbon monoxide

Answer 1

The correct option is D Carbon monoxide

The electron transport chain (ETC) occurs in the inner mitochondrial membrane that has four complexes that accept and carry electrons released from $NADH+H^{+}$ and $FAD{H}_2$. As the electrons move through different complexes, they release energy. This energy is utilized to pump protons from the matrix to the intermembrane space due to which a proton gradient is generated. Later the protons move through complex V (ATP synthase) into the matrix and there is synthesis of ATP.

Carbon monoxide is an inhibitor of complex IV of the ETC. Complex IV is cytochrome c oxidase. It has cytochromes a and $a_3$ , and two copper centres. This complex transports the electrons to the final electron acceptor i.e oxygen. Cytochrome $a_3$ is disrupted by the inhibitor, carbon monoxide.

Rotenone and amobarbital are inhibitors of complex I.

Antimycin A is an inhibitor of complex III of ETC.