USMLE

Methionine

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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

Methionine, which abbreviates to the 3-letter Met or single letter M, is one of the 20 amino acids that make up proteins in our body. Methionine’s R-group consists of a long hydrocarbon chain with a sulfur in the middle! Due to the composition of this R-group, methionine is also a non-polar, hydrophobic amino acid, with a neutral charge at physiological pH.

Key Points

  • Methionine
    • Abbreviations
      • Met, M
    • Chemical Structure
    • R-group: CH2-CH2-S-CH3 
      • Contrast vs. Cysteine
    • Polarity
      • Non-polar (lipid soluble/hydrophobic)
    • Charge at pH 7
      • Neutral (0)
    • Other Information
      • Part of tRNA initiation complex