Question

The CORRECT combination for metalloenzymes given in Column I with their catalytic reactions in Column II is 

• A. (i)–(M); (ii)–(N); (iii)–(K); (iv)–(L)
• B. (i)–(N); (ii)–(L); (iii)–(K); (iv)–(M)
• C. (i)–(N); (ii)–(K); (iii)–(L); (iv)–(M)
• D. (i)–(M); (ii)–(K); (iii)–(L); (iv)–(N)

Hint:

Remember key metal ions:
- Cytochrome P-450 → Fe (heme)
- Catalase → Fe (heme)
- Galactose oxidase → Cu
- Cytochrome c oxidase → Cu and Fe (binuclear center).

Answer 1

The Correct Option is C

Step 1: Identify each enzyme and its function.
(i) Cytochrome P-450: A heme enzyme responsible for hydroxylation reactions (monooxygenase activity). \[ \text{R–H} + O_2 + 2e^- + 2H^+ \rightarrow \text{R–OH} + H_2O \] Hence, (i) → (N).
(ii) Catalase: A heme enzyme that decomposes hydrogen peroxide. \[ 2H_2O_2 \rightarrow 2H_2O + O_2 \] Hence, (ii) → (K).
(iii) Galactose oxidase: Contains Cu as the metal center, catalyzing oxidation of alcohol to aldehyde. \[ \text{R–CH}_2\text{OH} + O_2 \rightarrow \text{R–CHO} + H_2O_2 \] Hence, (iii) → (L).
(iv) Cytochrome c oxidase: Final enzyme in the mitochondrial electron transport chain, catalyzing the reduction of oxygen. \[ O_2 + 4H^+ + 4e^- \rightarrow 2H_2O \] Hence, (iv) → (M).
Step 2: Combine results.
(i)–(N); (ii)–(K); (iii)–(L); (iv)–(M)
Step 3: Conclusion.
Correct answer is (C).