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JEE Main · 2019 · 09 Apr 2019 · Shift 2 · Biomolecules

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The peptide that gives positive ceric ammonium nitrate and carbylamine tests is:
  1. (A)Lys - Asp
  2. (B)Ser - Lys✓ Correct
  3. (C)Gln - Asp
  4. (D)Asp - Gln

Answer: (B)

Solution

The ceric ammonium nitrate test turns positive when a free hydroxyl group is present, while the carbylamine test is positive only for a primary amine, that is a free . Serine carries a hydroxyl group in its side chain, which answers the ceric ammonium nitrate test, and lysine carries a primary amino group in its side chain, which answers the carbylamine test. The dipeptide Ser-Lys therefore gives both tests positive.

JEE Main · 2019 · 09 Apr 2019 · Shift 2 · Single correct option

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