What is a one letter code of Tryptophan?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → W
Each of the twenty amino acids found in proteins has a three-letter symbol and a one-letter code. The one-letter code is the first letter of the name wherever possible (G for glycine, A for alanine, T for threonine). When two amino acids start with the same letter, the more common one gets that letter and the other is given a different letter.
Threonine already has T, so tryptophan (Trp) is coded W, a letter that sounds like the start of its name (“twyptophan”).
NCERT (2026-27 edition):
Amino Acids – …
