USMLE

Tryptophan

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Amino Acids
  1. Serine
  2. Asparagine
  3. Alanine
  4. Valine
  5. Leucine
  6. Isoleucine
  7. Phenylalanine
  8. Tryptophan
  9. Methionine
  10. Proline
  11. Glycine
  12. Threonine
  13. Cysteine
  14. Tyrosine
  15. Glutamine
  16. Aspartate
  17. Glutamate
  18. Histidine
  19. Lysine
  20. Arginine

Summary

Tryptophan, which abbreviates to the 3-letter Trp or single letter W, is one of the 20 amino acids found in proteins. Tryptophan’s R-group is an indole group, consisting of an aromatic benzene ring fused to a 5-sided ring containing nitrogen. Due to the overwhelmingly non-polar nature of this R-group, tryptophan is also a non-polar, hydrophobic amino acid, with a neutral charge at physiological pH.

Key Points

  • Tryptophan
    • Abbreviations
      • Trp, W
    • Chemical Structure
    • R-Group: -CH2-Indole
      • Indole
        • 6-membered benzene fused to 5-membered pyrrole ring
        • Bicyclic aromatic structure
    • Polarity
      • Nonpolar (lipid soluble/hydrophobic)
    • Charge at pH 7
      • Neutral (0)