UPSC Civil Services (Mains), Chemistry optional · 2025 · Paper I
Q5(e). Structure of [4Fe–4S] ferredoxin
Question
Draw the structure of Ferredoxin protein containing 4Fe–4S and find the average oxidation number of iron.
Answer in brief
A Fe₄S₄ cubane cluster held by four cysteine sulfurs; average oxidation number of Fe = 2.5 in the oxidised form, 2.25 in the reduced form.
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Coversferredoxiniron-sulfur clusterFe4S4 cubaneaverage oxidation stateelectron transfer proteinbioinorganic chemistry
All parts of Question 5
- 5(a) Activation energy from two rate constants5 marks
- 5(b) Light absorbed by a dye solution5 marks
- 5(c) Surface area of charcoal from a nitrogen monolayer5 marks
- 5(d) Showing that a decomposition is first order5 marks
- 5(e) Structure of [4Fe–4S] ferredoxin5 marks
- 5(f) Which complex has the larger Δₒ10 marks
- 5(g) Completing five p-block reactions10 marks
- 5(h) Magnetic moment: spin only in the d-block, not in the f-block5 marks