Glutamic Acid

Glutamic acid is one of the most common non-essential amino acids. German chemist Karl Ritthausen first isolated Glutamic acid from the wheat gluten in 1866, but its chemical structure was identified only in 1890.

Chemical Structure of Glutamic acid

Structure of Glutamic Acid

Identifiers and properties of Glutamic acid

IUPAC Name: (2S)-2-Aminopentanedioic acid
Symbol: Three-letter code - Glu. One-letter code - E
Molecular Weight (Molar Mass): 147.12926 g/mol
Molecular Formula (Structural Formula): C5H9NO4
Canonical SMILES: C(CC(=O)O)C(C(=O)O)N
Isomeric SMILES: C(CC(=O)O)[C@@H](C(=O)O)N
CAS Number: 56-86-0
MDL Number: MFCD00002634
Melting point: 205 °C
RNA codons: GAA, GAG
Solubility in water: 7,5 g/L (20 °C); pKa - 2,19; pKb - 9,67
Rf value in n-butanol/acetic acid/water = 12:3:5 - 0.30
2D Molfile: Get the molfile
3D PDB file: Get the PDB file
Other names: alpha-Aminoglutaric acid; L-2-Aminoglutaric acid; 1-Aminopropane-1,3-dicarboxylic acid; Glusate; Glutacid; alpha-Glutamic acid; L-Glutaminic acid; Glutaminol; Glutaton; (S)-2-Aminopentanedioic acid; Glutamate.

Glutamate or Glutamic Acid?

Glutamate and glutamic acid are closely related and often used interchangeably, but there is a chemical distinction between the two.

Glutamic Acid (Amino Acid). This is the natural form of the amino acid found in proteins. It contains a carboxylic acid group, making it acidic. In the context of proteins and amino acids, it is often referred to as glutamic acid.

Glutamate (Ion or Salt). Glutamate is the ionized form of glutamic acid, meaning it has lost a proton and carries a negative charge. In a solution or in the body, glutamic acid can lose a proton and become the ionized form, glutamate. When people refer to "monosodium glutamate" (MSG), they are referring to the sodium salt of glutamic acid.

In biological systems, especially in the human body, glutamic acid easily converts to glutamate in physiological conditions. So, in the context of discussing neurotransmitters, food flavor enhancers like MSG, or general physiology, the terms 'glutamic acid' and 'glutamate' are often used interchangeably.

For example, when discussing the role of glutamate as a neurotransmitter in the brain or its presence in food additives like MSG, it is more common to use the term 'glutamate'. On the other hand, when discussing amino acid composition in proteins, the term 'glutamic acid' may be used.

What is the role of L-Glutamic acid?

This amino acid is an excitatory neurotransmitter increasing the firing of neurons in the human central nervous system. Moreover, Glutamic acid is recognized as a major excitatory neurotransmitter in the human brain and in the spinal cord, transformted into Glutamine or Gamma-Aminobutyric Acid. This amino acid is necessary for proper cell functioning, but is considered as a non-essential amino acid, because human body is able to produce it.

Being one of the few nutrients able to pass through the blood-brain barrier, this amino acid appears to support brain function. In other words, Glutamic acid turned out to be human brain's primary 'food'. When it reaches the brain, it utilizes all excess ammonia, which is a toxic waste product of metabolism, by transforming it into the amino acid called Glutamine. In fact, this conversion is the only way our brain employs in order to be detoxified, indicating that not only is Glutamine not toxic, but it also has some essential antioxidant properties.

Benefits of Glutamic acid

As for Glutamic acid, also called 'chemical messenger', it has been shown to help improve intelligence. Since it is also a messenger in human brain, it is able to enhance a clarity of thinking, mental alertness, and mood. That is why this amino acid has been used to help treat Parkinson's, fatigue, mental retardation, schizophrenia, muscular dystrophy, and alcoholism. Besides, it is believed to help shuttle potassium (an important mineral) across the blood-brain barrier and right into the spinal fluid.

Glutamic acid is also known for its ability to detoxify muscle cells. For example, when intense exercise leads to increasing levels of ammonia in muscle cells (which slows down a recovery), just as in the brain, this amino acid attaches itself to ammonia in order to form Glutamine. Besides, Glutamic acid is acting as an intermediary in the Kreb's cycle and is important for the carbohydrate metabolism.

Food sources

Certain foods naturally contain glutamates, and if you're mindful of your glutamate intake, it's advisable to exercise caution with the following.

Cheese. Parmesan and Roquefort cheeses have the highest glutamate levels, with 1,680 mg and 1,280 mg per 100g, respectively.

Asian Sauces. Soy sauce can contain up to 1,700 mg of glutamate per 100g due to its natural high glutamate content. Fish sauce and oyster sauce are also noteworthy, containing 900 mg of glutamate per 100g in the case of oyster sauce.

Nuts. Walnuts are rich in glutamate, boasting 658 mg per 100g. It's crucial to be cautious with walnut butters and walnut oil, as they also concentrate levels of this amino acid.

Processed Meats. Cured ham, whether canned, frozen, or from the deli counter, should be avoided by those concerned about glutamate. It contains 340 mg of glutamate per 100g, and a second serving could easily lead to a significant intake.

Tomatoes. Fresh tomatoes are a source of glutamate, with up to 250 mg per 100g. It's important to extend this caution to tomato-based products like sauces and soups, as they can contribute substantially to your overall glutamate intake.

Juices. Grape juice contains moderate levels of glutamate, with 250 mg per 100g (about ⅔ of a cup). Avoiding it is recommended if you are aiming to limit your glutamate consumption. Additionally, tomato juice is another beverage to be wary of due to its high glutamate content..

Seafood. Some fish, such as anchovies, have moderate amounts of glutamate, with a 100g serving containing 630 mg. Scallops (160 mg per 100g) and oysters (150 mg per 100g) also contribute to overall glutamate intake.

Mushrooms. Dried shiitake mushrooms are particularly high in glutamate, boasting 1,060 mg per 100g. While white button mushrooms have less, at 180 mg per 100g, those seeking to eliminate glutamate from their diets might choose to avoid mushrooms altogether

Peas. A 100g serving of peas contains 200 mg of glutamate. While peas are a good source of various nutrients, those mindful of glutamate intake should moderate their portion sizes.

Starchy Vegetables. Corn and potatoes contain relatively low amounts of glutamate, around 100 mg per 100g. However, for individuals sensitive to glutamate, managing portion sizes is crucial.

It's important to note that these values are approximate and can vary based on factors such as specific product brands, preparation methods, and variations in nutrient content. If you have specific dietary concerns or need precise information about the glutamic acid content in foods, it's recommended to consult with a registered dietitian or refer to detailed nutritional information provided by food manufacturers.