Glutamic Acid Structure, Characteristics:13 Complete Quick Facts


In this article, we deal with glutamic acid structure and its chemical nature.

Glutamic acid having a molecular formula of C5H9NO4 belongs to the alpha-amino acid group and plays an important role in the synthesis of proteins inside the body and also acts as an excitatory neurotransmitters.

What is the structure of Glutamic Acid?

A typical amino acid comprises two chemical groups one is amino (NH2) and the other is the carboxylic acid group  (COOH). As glutamic acid comes under the category of amino acids. Therefore, it must satisfy all the criteria of amino acids.

Generally, amino acids are those chemical compounds found inside the living systems and act as building blocks for the synthesis of proteins. Now as the name glutamic acid indicates itself, it contains one extra acidic group which is acceptable for its acidic property. The structure of glutamic acid is given below:

glutamic acid structure

glutamic acid structure (containing one NH2 group and two COOH)

How to draw Glutamic Acid lewis structure?

Lewis structure or lewis dots of complex organic structure helps in predicting the number of lone pairs carried by the atoms involved in the structure. Let’s draw the lewis dots for glutamic acid structure one by one:

1. Let’s count the number of atoms involved in the structure and write down the electronic configuration of each atom.

Carbon (z=6)  [He] 2s22p2

Hydrogen (z= 1)  1s1

Oxygen (z=8)  [He] 2s²2p⁴

Nitrogen ( z= 7)  [He] 2s22p3As glutamic acid is a complex organic molecule. Hence the rule of placing an atom in the centre based on electronegativity does not apply here.

2. Now arrange all the atoms in such a way that the valency of each atom will satisfy.

3. Non-bonding electrons of the atoms which do not participate in bonding are represented by dots on the outside of the intended molecule.

     Lewis dots for glutamic acid

                                              

However in the real world, glutamic acid does not exist as a neutral molecule. Instead of it, all amino acids exist in zwitter ion.

What are zwitter ions?

Zwitter ions are those ions which comprise both cationic and anionic charges at the same time. Zwitter ions are also known as inner salts. As shown in the below figure, zwitter ions are formed when tautomerism takes place via the movement of hydrogen towards the lone pairs of the nitrogen of the amino group.

 Zwiter ions formations in glutamic acid structure

                                    

Is glutamic acid polar or nonpolar?

Glutamic acid is polar in nature. As a group is called to be polar in nature only when it is capable of forming either intra or inter-hydrogen bonding Hence, according to the definition of polar groups, glutamic acid is capable of forming hydrogen bonding as shown in the given figure:

Glutamic acid is involved in hydrogen bonding with another amino acid lysine

Is glutamic acid an amino acid?

 Amino acids are those organic molecules which consist of two characteristics groups in their structure; one is the COOH group with the NH2 group and also an additional side chain. As per the definition of amino acid, glutamic contains both the COOH group and also NH2 group. Hence glutamic acid is an amino acid.

Is glutamic acid an essential amino acid?

Glutamic acid can be formed by the body itself and hence, it comes under the non-essential category of amino acids as non-essential amino acids are those acids which can be synthesized by the body system itself whereas essential amino acids are those acids which can not be synthesized by the body system itself .

In nature, a total of 20 amino acids exist, out of which 8 are essential and the other 12 are non-essential.

The list of essential and non-essential amino acids is given below:

Non-Essential amino acidsEssential amino acids
AlanineTryptophan
ArginineIsoleucine
AsparagineLeucine
Aspartic acidLysine
CysteineMethionine
Glutamic acidHistidine
GlutaminePhenylalanine
ProlineThreonine
Glycinevaline
Serine
Tyrosine
List of essential and non-essential amino acids (wikipedia)

Is glutamic acid positive or negative?

In the case of glutamic acid, it carries two COOH groups which are accountable for the negative charge of the entity whereas the NH2 group hold for the positive charge of the structure. Since one negative cancel with one positive and left with one negative COOH group. Hence it is negative.

Is glutamic acid soluble in water?

Water is polar in nature and hence according to the rule “like dissolves like” ie if the compounds shared similar characteristics. They can be easily soluble in nature. As we know glutamic acid is also polar and hence it can be easily soluble in the water molecule.

Is glutamic acid acidic basic or neutral in nature?

As we already have idea of the zwitter structure of glutamic acid, it carries negative charge overall. Hence, according to definition of acidic amino acid, it carries negative charge at certain pH. Therefore glutamic acid is acidic in nature.

To better understand the difference between the acidic, basic and neutral amino acids let’s go through the following definitions.

Acidic amino acids: carry a negative charge at certain pH. For example Aspartic and glutamic acids

Basic amino acids: that carry a positive charge at certain pH. For examples arginine (Arg), lysine (Lys), and histidine (His).

Neutral amino acids: that carry neither negative nor positive charge are called neutral amino acids.  For example Glycine (Gly) and alanine (ala).

Is glutamic acid a protein?

As we know glutamic acid is an amino acid hence it is a constituent of the protein, not a protein. Therefore, glutamic acid is an amino acid, not a protein. In addition, human body don’t need to depend upon any external source of food to acquire it inside the body.

To get a clear picture, one should aware about the basic difference between a amino acid and proteins.

Proteins are those complex chemical structures found inside the human system which participate in those important chemical reactions inside the body which are essential for life.

On the other hand, proteins are made up of hundreds or thousands of smaller units called amino acids. Hence, amino acids are building blocks for the synthesis of proteins.

Is glutamic acid a strong acid?

In 20 amino acids, two amino acids are acidic in nature ie glutamic acid and aspartic acid. However, glutamic acid is less acidic as it contains one additional  CH2 group comparatively to aspartic acid. Moreover, the acidic character of the glutamic acid exists due to the formation of its zwiter ions which makes it a strong acid but less than the aspartic acid.

Acidic character comparison between Aspartic and glutamic acid

Is glutamic acid a proton donor?

Yes, glutamic acid is a proton donor. This is because as it donate the proton the resultant negative charge which is formed can be delocalised and add stability to the structure. This is the reason glutamic acid is less stable in comparison to its zwitter ion structure.

Is glutamic acid a lipid?

 Lipids are that category of chemical compounds which are fatty acids or their respective derivatives. They are usually hydrophobic ie does not dissolve in water and are only soluble in some organic solvents. For example waxes, steroids and natural oils. Since glutamic acid is soluble in water. Therefore, it cannot be a lipid.

Conclusion

To conclude, we learn about the structure of the glutamic acid, the steps involved in lewis structure for the same, its acidic nature and how it is related to the non-essential class of amino acids.

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