Question

Match the standard/stated cofactors in Column I with their respective enzymes in Column II 

• A. P – (v); Q – (ii); R – (iv); S – (i); T – (iii)
• B. P – (ii); Q – (iv); R – (v); S – (iii); T – (i)
• C. P – (iv); Q – (ii); R – (iii); S – (i); T – (v)
• D. P – (ii); Q – (i); R – (iii); S – (iv); T – (v)

Hint:

Remember cofactors: Cu$^{2+}$ → Cytochrome oxidase, Se → Glutathione peroxidase, Ni$^{2+}$ → Urease, K$^{+}$ → Pyruvate kinase, Mo → Nitrogenase. These are classical exam favorites in biochemistry.

Answer 1

The Correct Option is B

Step 1: Cu²⁺ (Copper)
Copper ions are essential cofactors of cytochrome oxidase (Complex IV of mitochondrial ETC), where Cu centers participate in electron transfer and O₂ reduction.
⇒ P – (ii).

Step 2: Se (Selenium)
Selenium is present as selenocysteine in glutathione peroxidase, an antioxidant enzyme reducing peroxides.
⇒ Q – (iv).

Step 3: Ni²⁺ (Nickel)
Nickel is a structural and catalytic cofactor for urease, which hydrolyzes urea into ammonia and CO₂.
⇒ R – (v).

Step 4: K⁺ (Potassium)
Potassium ions are important cofactors in glycolytic enzymes such as pyruvate kinase, stabilizing negative charges on phosphates.
⇒ S – (iii).

Step 5: Mo (Molybdenum)
Molybdenum is a cofactor for dinitrogenase (nitrogenase complex) in nitrogen-fixing bacteria, enabling N₂ reduction to NH₃.
⇒ T – (i).

Therefore, the correct matching is:
P – (ii), Q – (iv), R – (v), S – (iii), T – (i).