Question:medium
Selenocysteine is associated with which of the following?
Selenocysteine is associated with which of the following?
Show Hint
Think of the selenoenzyme that converts T4 to T3.
Updated On: Jun 24, 2026
- Carbonic anhydrase
- Catalase
- Deiodinase
- Transferase
Show Solution
The Correct Option is C
Solution and Explanation
Step 1: Begin with what makes selenocysteine special. It carries the trace element selenium and is incorporated co-translationally at the catalytic centre of a small family of redox enzymes called selenoproteins.
Step 2: Classic selenoproteins are glutathione peroxidase, thioredoxin reductase and the deiodinases. The deiodinase enzymes remove iodine from thyroid hormone, turning T4 into the metabolically active T3, and they depend on a selenocysteine residue for activity.
Step 3: Checking the choices against this list, deiodinase is the only true selenoenzyme present.
Step 4: The remaining enzymes rely on other cofactors. Carbonic anhydrase needs zinc, catalase needs an iron-porphyrin (heme), and transferase is just a broad reaction class, none of which involve selenium.
\[\boxed{\text{Deiodinase}}\]
Step 2: Classic selenoproteins are glutathione peroxidase, thioredoxin reductase and the deiodinases. The deiodinase enzymes remove iodine from thyroid hormone, turning T4 into the metabolically active T3, and they depend on a selenocysteine residue for activity.
Step 3: Checking the choices against this list, deiodinase is the only true selenoenzyme present.
Step 4: The remaining enzymes rely on other cofactors. Carbonic anhydrase needs zinc, catalase needs an iron-porphyrin (heme), and transferase is just a broad reaction class, none of which involve selenium.
\[\boxed{\text{Deiodinase}}\]
Was this answer helpful?
0
