Difference Between Glutamine and L-Glutamine

The key difference between glutamine and L-glutamine is that glutamine is an amino acid, whereas L-glutamine is an isomer of glutamine.

An amino acid is a simple molecule formed with C, H, O, N and maybe S. All amino acids have a –COOH, -NH2 groups and a –H bonded to a carbon. However, the R group differs from amino acid to amino acid. In the simplest amino acid, the R group is a hydrogen atm; we call it glycine. There are about 20 common amino acids. Some of them are essential to us while others are not essential. Glutamine is one of the main non-essential amino acids.

CONTENTS

1. Overview and Key Difference
2. What is Glutamine 
3. What is L-Glutamine
4. Side by Side Comparison – Glutamine vs L-Glutamine in Tabular Form
5. Summary

What is Glutamine?

Glutamine is one of the main amino acids which is not essential. We can abbreviate it as Gln. Its R group has an additional amine group. It is related to the structure of glutamic acid; however, glutamine has an amide side chain instead of the hydroxyl group of glutamic acid. Glutamine has the following structure.

Figure 01: Chemical Structure of Glutamine

Glutamine is the most abundant free amino acid in human blood. Its concentration in blood is about 500-900 µmol/L. Glutamine forms via the CAA and CAG codons. Moreover, it is synthesized from glutamate and ammonia in the presence of the glutamate synthetase enzyme. Mainly, it is mainly produced in muscles, and small amounts are released from lung and brain.

Glutamine has various functions in the biological systems. It participates in forming proteins as any other amino acids. Furthermore, glutamine is responsible for regulating the acid-base balance in kidneys. It functions as a nitrogen and carbon source as well as an energy source after glucose. The ammonia produced from the metabolic activities is toxic to cells when it is free. However, glutamine is a nontoxic way of transporting ammonia in the blood.

What is L-Glutamine?

L-glutamine is an isomer of glutamine amino acid. Glutamine is a chiral molecule which has non-superimposable mirror images. Therefore, there are two isomers of glutamine as L-glutamine and D-glutamine. Moreover, L-glutamine is abundant in the body and participates in various functions.

Figure 02: Structure of L-Glutamine

Furthermore, beef, chicken, eggs, fish, milk, cabbage, beets, beans, spinach and parsley are dietary sources of L-glutamine.

What is the Difference Between Glutamine and L-Glutamine?

Glutamine is a hydrophilic amino acid which is a constituent of most proteins. The key difference between glutamine and L-glutamine is that glutamine is an amino acid whereas L-glutamine is an isomer of glutamine. Moreover, Glutamine generally has two non-superimposable isomers as D-isomer and L-isomer while L-glutamine is one of the two isomers of glutamine. Therefore, we can consider this as another difference between glutamine and L-glutamine.

Apart from that, glutamine is the most abundant free amino acid in human blood, while L-glutamine is more abundant in organisms than the D-Glutamine. Also, when considering their usefulness, L-glutamine has more important applications than D-isomer and it is used as dietary supplements, to boost immune cell activity in the gut, etc.

The below infographic summarizes the difference between glutamine and L-glutamine.

Summary – Glutamine vs L-Glutamine

In summary, glutamine is a hydrophilic amino acid which is a constituent of most proteins. The key difference between glutamine and L-glutamine is that glutamine is an amino acid whereas L-glutamine is an isomer of glutamine.

Reference:

1. “Glutamine.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, pubchem.ncbi.nlm.nih.gov/compound/Glutamine.

Image Courtesy:

1. “L-Glutamin – L-Glutamine”By NEUROtiker – Own work (Public Domain) via Commons Wikimedia
2. “L-glutamine-skeletal” By No Benjah-bmm27 assumed (based on copyright claims). – No machine-readable source provided. Own work assumed (based on copyright claims). (Public Domain) via Commons Wikimedia

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