Aspartate, which abbreviates to the 3-letter Asp or 1-letter D, is one of the 20 amino acids that make up proteins in our body. Aspartate’s R-group consists of a carboxylic acid at the end of a short, 1-carbon chain. Due to this carboxyl group, aspartate is a polar, hydrophilic amino acid. The carboxylic acid can also act as a proton donor, making Aspartate an acidic, negatively charged amino acid at physiological pH. 

Key Points

  • Aspartate
    • Also known as Aspartic Acid
    • Abbreviations
      • Asp, D
    • Chemical Structure
    • R-group: -CH2-Carboxyl
      • Carboxyl
        • Contrast vs. Asparagine (which has amide instead of carboxyl)
        • “-ate” ending denotes ionic form of carboxylic acid
      • 1 bridging methylene carbon (-CH2-)
        • Contrast vs. Glutamate (which has 2 bridging carbons)
    • Polarity
      • Polar (water soluble/hydrophilic)
    • Acidity/Basicity
      • Acidic
      • pKa = 4 (rounded)
    • Charge at pH 7
      • Negative (-)
    • Other Information
      • Called Aspartic Acid when deprotonated