What Is Aspartic Acid?
Aspartic acid is one of the 20 natural amino acids that compose proteins. Discovered in asparagus sprouts, it is a nonessential amino acid in humans, meaning it can be synthesized by the body. It exists in both L- and D-forms. However, the L-form is the one incorporated into proteins.
Aspartic acid is an amphoteric ionic compound with an amino group (-NH2) and two carboxy groups (-COOH). Its charge is zero at the isoelectric point (pH 2.77), positive at lower pH levels, and negative at higher pH levels.
Physicochemical Properties of L-Aspartic Acid
- Name: L-aspartic acid (Japanese name), L-aspartic acid (English name), (2S)-2-aminobutanedioic acid (IUPAC name); 3-letter abbreviation: Asp; 1-letter abbreviation: D
- Molecular Formula: C4H7NO4
- Molecular Weight: 133.11
- Melting Point: 269-271°C
- Solvent Solubility: Insoluble in water, ethanol, and diethyl ether; soluble in acids and alkalis
- Taste: Umami, sour
Physiological Role of Aspartic Acid
Aspartic acid, found in nature as a protein constituent, is negatively charged in the physiological pH range due to its isoelectric point. This hydrophilic state makes proteins with high aspartic acid content soluble in water. Metabolically, aspartic acid is converted to oxaloacetic acid, an important intermediate in the TCA cycle for energy production in cells.
Benefits and Uses of Aspartic Acid
- Umami Ingredient: Aspartic acid, like glutamic acid, binds to umami receptors. It is used as a food additive in seasonings, carbonated beverages, refined sake, and powdered milk.
- Pharmaceuticals and Cosmetics: As an amphiphilic compound, aspartic acid stabilizes and solubilizes drugs and enhances moisturizing properties in cosmetics.
- Aspartame Raw Material: Aspartame, a dipeptide derivative of L-phenylalanine methyl ester and L-aspartic acid, is an artificial sweetener 200 times sweeter than sucrose.
Sources of Aspartic Acid
Aspartic acid is abundant in asparagus, sugar beets, potatoes, and beans.