What is the Difference Between Glutamate and Glutamic Acid

The main difference between glutamate and glutamic acid is that the glutamate is the anionic form of glutamic acid, which is one of the twenty essential amino acids that occur in both animals and plants. Furthermore, the glutamate serves as an excitatory neurotransmitter in the brain while the glutamic acid serves as an amino acid precursor in proteins. 

Glutamate and glutamic acid are two types of biomolecules in the body with distinctive functions. Glutamate serves as an excitatory neurotransmitter in the brain while glutamic acid helps in metabolism and serves as a constituent of proteins. 

Key Areas Covered 

1. What is Glutamate
     – Definition, Charge, Importance
2. What is Glutamic Acid
     – Definition, Structure, Importance
3. What are the Similarities Between Glutamate and Glutamic Acid
     – Outline of Common Features
4. What is the Difference Between Glutamate and Glutamic Acid
     – Comparison of Key Differences

Key Terms 

Amino Acid, Glutamate, Glutamic Acid, Monosodium Glutamate (MSG), Neurotransmitter

What is Glutamate 

Glutamate is the anion of glutamic acid formed by losing one hydrogen atom from the molecule. It is the main form of glutamic acid in the body under physiological conditions. Glutamate serves as an important neurotransmitter in the brain, which has an excitatory function, activating neurons. Also, glutamate serves as the precursor of GABA, which is the inhibitory neurotransmitter in the brain. In addition, glutamate is important for the disposal of nitrogen, a metabolic waste produced by protein metabolism. This process is called transamination.  

Figure 1: Glutamate

Due to the net negative charge on glutamate, it can bind with a cation such as sodium or potassium. When glutamate is bound to sodium, it is called monosodium glutamate (MSG). MSG is a synthetic form of glutamate produced outside of the body. Hence, glutamic acid in monosodium glutamate significantly differs from glutamic acid in a natural protein. The form of glutamic acid produced by the body is L-glutamic acid. But, MSG contains impurities such as D-glutamic acid and pyroglutamic acid, which accumulate carcinogenic mono and dichloro propanols inside the body while converting them into L-glutamic acid. However, MSG is usually used as a food additive to enhance the flavor, mainly in Chinese recipes.  

What is Glutamic Acid 

Glutamic acid is one of the 20 amino acids involved in protein synthesis as a building block. The side chain of it is CH₂CH₂COOH. However, since the human body can produce it through metabolism, glutamic acid is not considered as an essential amino acid. However, it can be taken from plant and animal sources as food. 

Figure 2: Aspartic Acid

Similarities Between Glutamate and Glutamic Acid 

• Glutamate and glutamic acid are two types of biomolecules in the body. 
• Both consist of five carbon atoms: two carboxyl groups and one amino group. 
• The amino acid form can be synthesized by the body. 

Difference Between Glutamate and Glutamic Acid 

Definition 

Glutamate refers to the salt of glutamic acid while glutamic acid refers to an acidic amino acid which is a constituent of many proteins.  This is the basic difference between glutamate and glutamic acid.

Charge 

Another difference between glutamate and glutamic acid is that the glutamate bears a net negative charge while the glutamic acid is a neutral molecule. 

Occurrence 

Moreover, while glutamate is the form that exists in the body under physiological conditions, glutamic acid is always converted into glutamate. 

Role in the Body 

One other main difference between glutamate and glutamic acid is that the glutamate serves as an excitatory neurotransmitter in the brain and serves as the precursor molecule for the production of GABA while the glutamic acid serves as an amino acid precursor in proteins. 

Conclusion 

Glutamate is the anionic form of glutamic acid which bears a net negative charge. Glutamic acid is one of the twenty amino acids that serves as a building block in protein synthesis. It occurs in both plants and animals. The human body also can synthesize glutamic acid. Glutamate is the physiological form of glutamic acid. It serves as an important neurotransmitter in the brain and plays a vital role in protein metabolism called transamination reactions. The main difference between glutamate and glutamic acid is their charge and importance. 

Reference:

1. Misner, William. “Monosodium Glutamate MSG, Glutamic Acid Glutamate, Glutamine Review.” Hammer Nutrition, Available Here

Image Courtesy:

1. “L-Glutamate Structural Formulae” By Jü – Own work (Public Domain) via Commons Wikimedia   
2. “L-Glutaminsäure – L-Glutamic acid” By NEUROtiker – Own work (Public Domain) via Commons Wikimedia