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Last updated date: 16th May 2024
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What is Serine?

Serine is described as a non-essential amino acid that can be used in the biosynthesis of proteins. These are derived from the amino acid glycine. And, they are obtained by the process of hydrolysis. These acids do not need any literary resources and are synthesized from glucose.

About Serine

L-isomer is one and the only form of Serine that is involved in the process of protein synthesis in humans. It is considered one of the twenty amino acids that are needed for normal body functioning. Since it is a type of non-essential amino acid, it can be synthesized by the human body from many compounds via various chemical reactions. Serine acid forms an integral part of the phospholipids class that is found in the biological membrane, where Ethanolamine is an example.

Structure of Serine

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The word amino acid in biochemistry categorically refers to the alpha-amino acids primarily consisting of the carboxyl group and amino. The structure of alpha-amino acid is illustrated as follows.






Where R is given as the Side Chain that is specific to every amino acid.

These two optical isomers of amino acids are termed L and D. They also represent the huge majority of amino acids that sunder in many amino acids. Also, they actively participate in protein synthesis. However, mammalian protein synthesis involves only L-Stereoisomers.

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Occurrence of Serine

This compound is one of the most naturally occurring amino acids of proteinogenic. Only L-stereoisomer naturally appears in proteins. It is not required in the human diet because it is synthesized in the body from the other metabolites, including glycine. Serine was first obtained in 1865 from the silk protein, which is a specific rich source, by Emil Cramer. The name was derived from the Latin for silk, known as sericum. At the same time, the structure of Serine was established in 1902. Food sources containing high L-Serine content among their proteins include edamame, eggs, lamb, pork, liver, salmon, seaweed, sardines, tofu, and many more.

Function of Serine

Let us look at the important functions of Serine

Serine plays an essential role in the synthesis of several biological vital compounds, namely cysteine, glycine, purines, phosphides, pyrimidines, proteins, and many more. It also plays a vital role in metabolism. Serine protease, which is found in the digestive system, breaks down the proteins that help an enzyme catalyze in its chemical reaction.

A serine protease is defined as an enzyme that sunders the peptide bonds in proteins. They are found in eukaryotes and prokaryotes. The side chain of Serine as a residue of proteins can undergo O-linked glycosylation. The residues of the phosphorylated Serine are referred to as phosphoserine. Also, D-Serine consists of a musty aroma, and it is an off–white crystalline powder. In contrast, L- Serine tastes sour at much higher concentrations.


Phosphatidylserine (otherwise called PS or Ptd-L-Ser) is a phospholipid and is more specifically described as a glycerophospholipid. It contains two fatty acids that are attached in ester linkage to both the first and second carbon of glycerol, and the series will be attached through a phosphodiester linkage to the glycerol’s third carbon.

Phosphatidylserine also helps in blood coagulation (called clotting). It is a cell membrane component and plays a vital role in the cell cycle signalling, specifically in relation to apoptosis. It is defined as a key pathway for viruses to enter cells through apoptotic mimicry.

Phosphatidylserine can be found in several food products that we take. It is also noted that the ones coming from animals and the ones coming from the plants differ in fatty acid composition. It is present in chickens, pigs, turkeys, and milk for animal sources and also in rice, potato, carrot, and barley for plant sources.


Sirtuins are the family of NAD-dependent protein deacetylases that are present in various cellular components. They promote the expression of genes whose products increase the life span.

Before going into the details regarding how Sirtuins help increase longevity, we should first reflect upon the reasons that cause ageing.

Most of the Common Causes of Ageing Are Given as Follows

  • Increased free radicals and decreased levels of the antioxidants present in the body.

  • Telomere shortening (Telomeres are the short DNA stretches at the end of the chromosome that get shortened after every cell division).

  • Increased collagen cross-linking (most be the abundant protein of the human body).

Now Coming Back to the Action of Sirtuins Mechanism, They Prolong a Life Span in the Following Ways:

  • Inhibition of the apoptotic and metabolic activity of the cell.

  • Reducing the damage occurred by free radicals.

  • Increasing the metabolism of glucose that increases insulin sensitivity of the body.

An interesting thing about the Sirtuins is that they get induced by the Calorie restriction (hence, we should listen carefully to our dietician or nutritionist) and a component present in the red wine.

FAQs on Serine

1. Explain the metabolic function of Serine?

Serine is much important in metabolism, where it participates in the biosynthesis of pyrimidines and purines. It is also the precursor to many amino acids, including cysteine and glycine, and tryptophan in bacteria as well. It is also defined as the precursor to many other metabolites, including folate and sphingolipids, which is the principal donor of the one-carbon fragments present in biosynthesis.

2. How many amino acids does a protein contain?

There exists a total of 20 natural amino acids that makes up the protein in our body. Every amino acid contains a three-letter code known as a codon, and about 61 of such combinations are present in humans. All these combinations make peptide chains, and those chains further fold to produce proteins.

3. What happens if the Serine is mixed with alanine and glycine?

They can produce peptide bonds, but whether they will depend on the information that is not provided. In this case, if they form peptide bonds, they can have secondary and tertiary structures. However, it is not really sure where we are going with this. Also, we are not going to magically get an enzyme if we are expecting, and as per the definition, a protein is described as a polypeptide with a function. So, we are not going to get a protein either, especially with simply three amino acids.

4. How does the Serine is synthesized?

Serine can also be synthesized in the human body under the regular physiological circumstances by making it a non-essential amino acid. It is also encoded with codons' help, including UCC, UCU, UCG, UCA, AGC, and AGU.