Arginine

Summary

Arginine is one of 20 amino acids that make up proteins in our body. It is abbreviated to the 3-letter Arg and the 1-letter R. Arginine’s R-group starts with a 3-carbon chain, followed by a guanidino group, which is a three-pronged structure with nitrogens at the end of each prong. As a result of these nitrogens, arginine is a polar, hydrophilic amino acid. The double bonded nitrogen also acts as a proton acceptor, making arginine a basic, positively charged amino acid at physiological pH.

Key Points

• Arginine
  • Abbreviations
    • Arg, R
  • Chemical Structure
    • 
  • R-group: -CH2-CH2-CH2-Guanidino
  • Polarity
    • Polar (water soluble/hydrophilic)
  • Acidity/Basicity
    • Basic
    • pKa = 12.5 (rounded)
  • Charge at pH 7
    • Positive (+)