USMLE

Phenylalanine

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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

Phenylalanine, which abbreviates to the 3-letter Phe or the single letter F, is one of the 20 amino acids used to build proteins in our body. Phenylalanine’s R-group is a benzyl group: that is, an aromatic benzene ring connected by a single bridging carbon.  Because of this non-polar R-group, phenylalanine is also a non-polar, hydrophobic amino acid, with a neutral charge at physiological pH.

Key Points

  • Phenylalanine
    • Abbreviations
      • Phe, F
    • Chemical Structure
    • R-Group: -CH2-benzene
      • Aromatic benzene ring
        • Aromatic compounds absorb UV light
      • No hydroxyl group (contrast vs. Tyrosine)
    • Polarity
      • Non-polar (lipid soluble/hydrophobic)
    • Charge at pH 7
      • Neutral (0)