USMLE

Lysine

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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

Lysine is one of the 20 amino acids that make up proteins in our body. It is abbreviated to the 3-letters Lys and the 1-letter K. Lysine’s R-group consists of an amino group at the end of a long, 4-carbon chain. As a result, lysine is a polar, hydrophilic amino acid. The nitrogen in the amino group also acts as a proton acceptor, making lysine a basic, positively charged amino acid at physiological pH. 

Key Points

  • Lysine
    • Abbreviations
      • Lys, K
    • Chemical Structure
    • R-group: -CH2-CH2-CH2-CH2-NH2 
    • Polarity
      • Polar (water soluble/hydrophilic)
    • Acidity/Basicity
      • Basic
      • pKa = 10.5 (rounded)
    • Charge at pH 7
      • Positive (+)