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)