Multiple choice

Which of the following amino acids gives Hopkins Cole colour reaction?

  1. Glycine

  2. Serine

  3. Tryptophan

  4. Histidine

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Hopkins-Cole reaction (also called glyoxylic acid test) is specific for tryptophan, which contains an indole ring that reacts with glyoxylic acid in presence of concentrated sulfuric acid to form a purple-colored product. Glycine, serine, and histidine do not contain indole rings and do not give this reaction.