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Glutamic Acid

Like carbohydrates and nucleic acids, proteins are also polymers of amino acids formed by the condensation polymerization. One or more amino acids are bonded together through an amide linkage also called as peptide linkage and for peptides. On the basis of number of amino acids in peptide, they termed as di peptied, tri peptide etc.

If more than 100 amino acids joined together to form long peptide chain, it called as polypeptide chain which further oriented in three dimensional space to form different levels of proteins. Only α-amino acids are involve in protein formation in which both functional groups (-COOH and -NH2) bonded on same carbon atom of molecule. There are total twenty amino acids involve in different protein synthesis through various sequence in polypeptide chain.

Amino acids Structure Abbreviation
Alanine CH3-CH(NH2)-COOH ala A
Arginine HN=C(NH2)-NH-(CH2)3-CH(NH2)-COOH arg R
Asparagine H2N-CO-CH2-CH(NH2)-COOH asn N
Aspartic Acid HOOC-CH2-CH(NH2)-COOH asp D
Cysteine HS-CH2-CH(NH2)-COOH cys C
Glutamic Acid HOOC-(CH2)2-CH(NH2)-COOH glu E
Glutamine H2N-CO-(CH2)2-CH(NH2)-COOH gln Q
Glycine NH2-CH2-COOH gly G
Histidine NH-CH=N-CH=C-CH2-CH(NH2)-COOH his H
Isoleucine CH3-CH2-CH(CH3)-CH(NH2)-COOH ile I
Leucine (CH3)2-CH-CH2-CH(NH2)-COOH leu L
Lysine H2N-(CH2)4-CH(NH2)-COOH lys K
Methionine CH3-S-(CH2)2-CH(NH2)-COOH met M
Phenylalanine C6H5-CH2-CH(NH2)-COOH phe F
Proline NH-(CH2)3-CH-COOH pro P
Serine HO-CH2-CH(NH2)-COOH ser S
Threonine CH3-CH(OH)-CH(NH2)-COOH thr T
Tryptophan C6H5-NH-CH=C-CH2-CH(NH2)-COOH trp W
Tyrosine HO- C6H4-CH2-CH(NH2)-COOH tyr Y
Valine (CH3)2-CH-CH(NH2)-COOH val V


Glutamic Acid Amino Acid

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Out of twenty amino acids, there are two amino acids which have two carboxyl groups with one amino group, hence acidic in nature. They are Glutamic acid and aspartic acid. The second carboxyl group bonded in side chain of amino acid molecule. Another name used for Glutamic acid is glutamate due to the deprotonation of carboxyl group present in side chain creates negative charge at physiological pH from 7.35 to 7.45. It is a white crystalline powder with the molecular formula C5H9NO4 and molecular weight 147.1 g/mol.

There are three functional groups.

$\alpha$-COOH group ($pK_{a}$: 2.10),
$\alpha$-NH2 group ($pK_{a}$: 9.47) and side chain -COOH group with $pK_{a}$ 4.07.

The carboxyl group bonded on side chain is more acidic in Glutamic acid compare to aspartic acid due to the positive inductive effect of one methyl group present in Glutamic acid.

Like other amino acids, it is easily soluble in water (8.64 g/l (298K)) and sparingly soluble in alcohols. It is a non-essential amino acid with codons GAA and GAG. The presence of chiral carbon atom makes Glutamic acid optically active and shows dextrorotary and levorotatory form as well as racemic mixture. Out of these two forms, levo-form is more common.

Different Configurations of Glutamic acids are as follows.
Configurations of Glutamic Acids

Glutamic acid is a non-essential amino acid, thus can be synthesis in body during different biosynthesis processes. Some common enzyme catalyzed biosynthesis processes for Glutamic acid are as follow.

Reactants Products Enzymes
Glutamine + H2O $\to$ Glutamic acid + NH3 Glutaminase, GLS2
N-Acetylglutamic acid (NAcGlu) + H2O $\to$ Glutamic acid + Acetate (unknown)
$\alpha$-ketoglutarate + NADPH + NH4+ $\to$ Glutamic acid + NADP+ + H2O Glutamate dehydrogenase 1 (GLUD1), GLUD2
$\alpha$-ketoglutarate + $\alpha$-amino acid $\to$ Glutamic acid + $\alpha$-keto acid transaminase
1-Pyrroline-5-carboxylate + NAD+ + H2O $\to$ Glutamic acid + NADH Aldehyde dehydrogenases(ALDH4)
N-formimino-L-glutamate + FH4 $\to$ Glutamic acid + 5-formimino-FH4 Formiminotransferase cyclodeaminase (FTCD)

Glutamic acid is an important intermediate in Krebs cycle with $\alpha$-ketoglutarate as both are inter convertible by trans amination process.

Glutamate + H2O + NADP+$\to$ $\alpha$-ketoglutarate + NADPH + NH3 + H+

Similarly Glutamic acid enters the Krebs cycle for energy metabolism, and get converted to glutamine in the presence of glutamine synthetase enzyme via the formation of $\gamma$-glutamyl phosphate as an intermediate.
Glutamine Synthetase

Glutamic acid also acts as precursor for the synthesis of proline. Glutamic acid is reduced to the aldehyde to form glutamate semi aldehyde which further reacts with the $\alpha$-amino group and form Schiff base with the elimination of water molecule. The Schiff base is further reduced to final product that is proline.

Glutamic Acid Structure

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Glutamic acid is an acidic and polar amino acid with one carboxyl group in its side chain.

Aspartic Acid

Since in Glutamic acid there is an additional methylene group compare to aspartic acid which impart positive inductive effect, increases the acidity of molecule.

Isoelectric Point of Arginine

The zwitterion of Glutamic acid is negatively charged with isoelectric point of 3.22.

Glutamic Acid Hydrochloride

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Glutamic Acid Hydrochloride
  1. Glutamic acid hydrochloride is a white crystalline powder with molecular formula C5H10ClNO4 and formula weight 183.59.
  2. The melting point of Glutamic acid hydrochloric is 487K with density 1.525 and refractive index $24^{\circ}$.
  3. It's easily soluble in water around 490 g/L at 293K. Glutamic acid hydrochloride is often used as flavor food or as a supplement to promote digestion.
  4. It can be useful for other patients with low acid secretion like diabetics.
  5. They can also function as an anti-aging supplement as it can to both external aging, like wrinkles and age spots and internal aging, like periodontal disease and digestive disorders.
  6. Glutamic acid hydrochloride is also found in pill form or as white powdered substance and commercially as an ingredient in various protein supplement powders.

Glutamic Acid Benefits

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A German chemist, Karl Heinrich Leopold Ritthausen first isolated Glutamic acid, glutamate or also known as Theanine is a non essential amino acid in 1866. Glutamic acid is good for neurological brain function and metabolism.

It is a non-essential amino acid which is produced in the body by various biosynthesis process, thus the body does not require a dietary intake of this amino acid.
  1. Glutamic acid is an essential neurotransmitter for normal, healthy brain function. It is also known in its salt form which termed as glutamate which is an excitatory neurotransmitter in the brain and spinal cord and can increases the firing of neurons in the central nervous system. By different biochemical reactions which are catalysed by enzymes, Glutamic acid can form Glutamine and Gamma-Aminobutyric Acid (GABA) that help pass messages to the brain. Glutamic acid can stimulate the neurons in the nervous system by enhancing the brain nervous system interaction.
  2. Glutamic acid involves in detoxification of ammonia in brain and can be supplemented as a brain fuel. This amino acid is essential for various brain functions like learning, memory, problem solving etc.
  3. Glutamic acid involves in healthy active metabolism by converting sugars and fat into glucose and acts as main source of fuel.
  4. It is also used for the treatment of behavioral disorders and also helpful in preventing prostate enlargement along with glycine and Alanine amino acid.
  5. Glutamic acid can react some of the toxic substance like ammonia and convert it into glutamine which further converted to urea and excreted by the urine.
  6. It also useful in minimizing epileptic seizures and in the treatment of hypoglycemic comas which can occur with diabetics.
  7. The monosodium salt form of Glutamic acid (MSG) is used as a food preservative.
  8. Glutamic acid is used for the treatment of muscular dystrophy. A study proves that the deficiency of Glutamic acid is responsible for Duchenne muscular dystrophy. Hence Glutamic acid can reverse the deficiency and used for treatment.
  9. Glutamic acid therapy is also useful for the treatment of some other diseases like schizophrenia or bipolar disorder and Parkinson's disease.
  10. Glutamic acid is also helpful for the development of IQ for Mentally Challenged Individuals.
  11. Glutamic acid plays an important role in brain functions. It reacts with ammonia produced during various brain functions and improve mental alertness and thought processes. Glutamic acid also acts as a messenger in the brain and used for the treatment of many brain disorders.
  12. Muscle cells have high level of ammonia due to exercise which can be removed by Glutamic acid and convert it into glutamine which accelerate recovery of muscle cells.
  13. Glutamic Acid is also involved in metabolism of sugars and fats as well as in the transportation of potassium into the spinal fluid and blood-brain barrier which cannot be passed by Glutamic acid molecules. Hence it present in high concentration in blood and may infiltrate the brain in small amounts where brain can use glutamic acid as fuel.
  14. Glutamic acid is also used for the treatment of personality disorders, childhood behavioral disorders, epilepsy, muscular dystrophy, hypoglycemic coma, ulcers, mental retardation and a complication of insulin treatment for diabetes. It is a component of folic acid, a vitamin-B which helps the body break down amino acids.
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