Which statement accurately describes the role of iron-sulfur clusters in metabolism and their sensitivity to oxidative stress?

Which statement accurately describes the role of iron-sulfur clusters in metabolism and their sensitivity to oxidative stress?

• A. They are stable under oxidative stress.
• B. They store iron and sulfur for later use but do not participate in redox.
• C. They function only in chloroplasts.
• D. Iron-sulfur clusters participate in electron transfer and are highly sensitive to oxidative stress, leading to impaired function.

Answer: (D)

Iron-sulfur clusters are redox-active cofactors that shuttle electrons through many metabolic enzymes, including parts of the electron transport chain and several carbon metabolism steps. Their ability to cycle between oxidation states makes them ideal mediators of electron transfer. Yet their metal-sulfur cores are highly vulnerable to oxidative stress; reactive oxygen species can over-oxidize or disrupt the clusters, causing loss of enzyme activity and impaired metabolic function. This combination—participation in electron transfer and extreme sensitivity to oxidative damage—explains why oxidative stress specifically destabilizes Fe-S–containing enzymes and why the described statement is correct. They are not simply iron and sulfur stores, nor are they confined to chloroplasts; they are widespread in mitochondria, bacteria, and chloroplasts.

Iron-sulfur clusters are redox-active cofactors that shuttle electrons through many metabolic enzymes, including parts of the electron transport chain and several carbon metabolism steps. Their ability to cycle between oxidation states makes them ideal mediators of electron transfer. Yet their metal-sulfur cores are highly vulnerable to oxidative stress; reactive oxygen species can over-oxidize or disrupt the clusters, causing loss of enzyme activity and impaired metabolic function. This combination—participation in electron transfer and extreme sensitivity to oxidative damage—explains why oxidative stress specifically destabilizes Fe-S–containing enzymes and why the described statement is correct. They are not simply iron and sulfur stores, nor are they confined to chloroplasts; they are widespread in mitochondria, bacteria, and chloroplasts.