One-letter amino-acid code — The peptide abbreviation “WYQN” corresponds to which sequence of amino-acid names in order from N- to C-terminus?

Introduction / Context:
One-letter codes are widely used in bioinformatics, structural biology, and sequence annotation. Accurate decoding ensures correct interpretation of motifs, domains, and mutational data across databases.

Given Data / Assumptions:

• Sequence given: W Y Q N.
• Standard one-letter codes: W = tryptophan, Y = tyrosine, Q = glutamine, N = asparagine.
• We must match each letter to the correct full name.

Concept / Approach:
Memorized mappings (e.g., “Queen Q = glutamine,” “New N = asparagine,” “Why Y = tyrosine,” “Double ring W = tryptophan”) help recall. Care must be taken not to confuse Q (glutamine) with E (glutamic acid) or N (asparagine) with D (aspartic acid).

Step-by-Step Solution:

Verification / Alternative check:
Compare with standard IUPAC tables of one-letter amino-acid codes; W, Y, Q, N are unambiguous.

Why Other Options Are Wrong:

• Option (a) uses E (glutamic acid) instead of Q.
• Option (c) duplicates tryptophan and misplaces glutamine.
• Option (d) begins with glutamine and ends with aspartic acid (D), not N.

Common Pitfalls:
Confusing amide forms (Q, N) with their acidic counterparts (E, D). The side-chain amides are neutral at physiological pH, unlike their acidic forms.

Final Answer:
Tryptophan, tyrosine, glutamine, asparagine