Herpes disease is caused by herpes virus and can be cured by the drugs containing lysine. Lysine is an essential amino acid for the human body. Lysine is not only used in the treatment of herpes but for various other diseases as well. It also has many culinary applications. In this article we will discuss chemical aspects of lysine, its structure, sources and uses.
What is Lysine?
Lysine is an essential -amino acid which is found in many foods as protein. Its symbol is Lys or K. As we know amino acids are the basic structural units of protein, so Lysine is used in the synthesis of proteins. As it is an \[\alpha\] – amino acid so, it contains \[\alpha\] – amine group and \[\alpha\] – carboxylic acid group. We will discuss its structure in detail in the next section.
It is essential for our body, but our body cannot synthesize it on its own. So, it must be obtained from foods. Lysine helps in animal growth as well. That’s why Lysine supplements are used as animal feed, specially for chickens and pigs for their optimal growth and production of meat. Some plants and bacteria can synthesize lysine from aspartic acid which is also an amino acid. It is synthesized in organisms by mainly following two biosynthetic pathways –
Diaminopimelate pathway
\[\alpha\]– aminoadipate pathway
It was 1st isolated in 1889 by German Chemist Ferdinand Heinrich Edmund Drechsel from the casein phosphoprotein present in milk. Ferdinand Heinrich named lysine as ‘Lysin’. After almost thirteen years of its discovery and isolation, lysine was synthesized in 1902 by German Chemists Emil Fischer and Fritz Weigert. They determined the structure of the lysine as well.
As lysine is vital for many biological processes so its deficiency can cause many diseases such as anaemia, defects in tissues, protein energy deficiency etc. It is a vital organic compound for growth of plants and animals as well. Thus, lysine is an important – amino acid for various processes occurring in human beings, animals and plants as well.
Structure of Lysine
Lysine contains \[\alpha\] – amine group (In form of protonated -NH3+), \[\alpha\] – carboxylic acid group (In form of deprotonated -COO-), and a lysyl side chain [(CH2)4NH2] in its carbon chain. It is a covalent organic compound. It is encoded by the genetic codes AAA and AAG. It has a chiral \[\alpha\] – carbon. Its enantiomer L – Lysine in which \[\alpha\] – carbon is in the S configuration and is biologically active.
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Amino Acid Structure
\[\alpha\] – Carbon, amino group and carboxylic acid group are the backbone of lysine. Its chemical formula is C6H14N2O2. It is a linear amino acid molecule. Lysine is a base and water soluble. It forms hydrogen bonds with other molecules. Its structure formula L-lysine is given below –
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Structure of L- Lysine
General Structure of lysine –
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Foods Rich in Lysine or Sources of Lysine
Lysine is essential for proper growth and is used in biosynthesis of protein. As you know, lysine cannot be synthesized by our body and we must take it through diet. So, it becomes necessary for us to include lysine rich foods in our diet. As lysine is used in biosynthesis of proteins, so it naturally occurs in protein rich food items.
Meat (red meat), eggs, rajma, chickpeas, few species of fishes, soybeans, tofu, fenugreek seeds, cheese, pork, chicken etc. are good sources of lysine. Other beans, dairy products and Brewer’s yeast, mushroom also contain lysine.
Apart from these natural sources of lysine various other lysine supplements are also available. It is available in the form of tablets, capsules, creams and liquid solution form.
Function of Lysine
Lysine is necessary for the healthy functioning of the human body and some organisms, plants and animals. Catabolism of lysine takes place in the liver. Amino acids of lysine provide glucose to the human body through metabolism. It is metabolized into acetyl – CoA which forms adenosine triphosphate. Adenosine triphosphate is the currency of energy in our body. Lysine plays a vital role in the citric cycle in animals.
Allysine is a derivative of lysine which is used to produce collagen and elastin. These are essential for skin, joints etc.
Uses of Lysine
Lysine plays an important role in many biological processes. Its most common role is proteinogenesis. It is a base of protein structure. It is considered as amphipathic which means it shows both hydrophilic and lipophilic properties. Because of this it becomes even more important for various processes. Its amino group forms hydrogen bonds, covalent bonds and salt bridges with other molecules. Therefore, lysine contributes to protein stability as well. Lysine plays a major role in epigenetic regulation. Many histone modifications involve lysine. These modifications can affect gene regulation.
Lysine plays a key role in calcium homeostasis and fatty acid metabolism. It is involved in the crosslinking of helical polypeptides in collagen. It is a precursor for carnitine. Carnitine transports fatty acids to the mitochondria.
Lysine is useful in treatment of herpes. Herpes is caused by herpes simplex virus. Arginine promotes the growth of herpes simplex virus and lysine blocks the activity of arginine.
It helps the body to absorb calcium. As calcium is a must for healthy bones. So, researches show that lysine helps in prevention of osteoporosis.
Sometimes athletes take lysine supplements as protein supplements as studies show that lysine helps muscles to recover faster after stress.
Lysine is used as animal feed as it helps in their optimal growth. Thus, lysine is a key ingredient of food, which is used in poultry farms, pig farming etc. to feed chickens, pigs and other animals for their optimal growth and high - quality meat.
Early studies show that lysine is effective in treatment of canker sores and diabetes. Studies state that it can even prevent canker sores and diabetes. It reduces the blood sugar level. Lysine is helpful in reducing the stress as well.
A derivative of lysine is used in pain management as it serves as an anti – inflammatory agent. It can be helpful in preventing cardiovascular diseases and blood pressure fluctuations.
Deficiency of Lysine
As lysine plays key roles in many biological processes and essential for our body, so its deficiency causes various diseases also. Most of the diseases due to lysine are the result of downstream processing of lysine. Lack of lysine causes disease related to connective tissues. Lack of lysine may cause lack of carnitine levels in the body which may cause many health - related issues as carnitine transfers fatty acids to mitochondria and mitochondria is known as powerhouse of the cells. Deficiency of lysine may cause anaemia, protein energy malnutrition, neurological disabilities, epilepsy, ataxia and psychomotor impairment.
This ends our coverage on the topic “Lysine”. We hope you enjoyed learning and were able to grasp the concepts. We hope after reading this article you will be able to solve problems based on the topic. If you are looking for solutions of NCERT Textbook problems based on this topic, then log on to Vedantu website or download Vedantu Learning App. By doing so, you will be able to access free PDFs of NCERT Solutions as well as Revision notes, Mock Tests and much more.
FAQs on Lysine
1. What is Lysine and how is it classified as per the CBSE syllabus?
Lysine is an α-amino acid, which means it has an amino group and a carboxyl group attached to the same carbon atom (the α-carbon). According to the NCERT curriculum, amino acids are classified based on the nature of their side chain (R-group). Since Lysine's side chain contains an additional amino group, it is classified as a basic amino acid.
2. What is the chemical structure of Lysine that makes it a basic amino acid?
The chemical structure of Lysine (C₆H₁₄N₂O₂) features a central α-carbon bonded to a hydrogen atom, a carboxyl group (-COOH), an α-amino group (-NH₂), and a side chain. The key feature is its side chain, which is a -(CH₂)₄-NH₂ group. The presence of this second amino group in the side chain, in addition to the α-amino group, gives Lysine two basic sites and only one acidic site (the carboxyl group). This excess of basic groups over acidic groups is what defines it as a basic amino acid.
3. Why is Lysine considered an essential amino acid for the human body?
Lysine is classified as an essential amino acid because the human body cannot synthesise it in sufficient quantities to meet its metabolic needs. Therefore, it must be obtained directly from the diet. Its importance lies in its role as a fundamental building block for proteins, which are crucial for growth, tissue repair, and the production of enzymes and hormones.
4. How does the structure of Lysine allow it to exist as a zwitterion?
Like all amino acids, Lysine can exist as a zwitterion, which is a dipolar ion. This occurs in aqueous solution when the acidic carboxyl group (-COOH) donates a proton to become a carboxylate ion (-COO⁻), and the basic amino groups (-NH₂) accept protons to become ammonium ions (-NH₃⁺). In a neutral solution, both of Lysine's amino groups are protonated, giving it a net positive charge. Its isoelectric point (pI)—the pH at which it has no net charge—is high (around 9.7) due to its basic nature.
5. What are the primary biochemical functions of Lysine in protein synthesis?
The primary biochemical function of Lysine is its role as a crucial component in protein synthesis. Its key functions include:
- Building Block: It is incorporated into polypeptide chains to form various proteins, including structural proteins like collagen and elastin.
- Post-translational Modification: The side chain of Lysine is often modified after protein synthesis (e.g., through methylation or acetylation), which can regulate protein function.
- Enzyme and Hormone Production: It is essential for synthesising carnitine, a substance that helps transport fats across cells to be burned for energy.
6. How does Lysine differ from an acidic amino acid like Aspartic acid in structure and properties?
The main difference between Lysine and Aspartic acid lies in their side chains (R-groups):
- Structure: Lysine has a side chain containing a second amino group (-NH₂), making it a basic amino acid. Aspartic acid has a side chain containing a second carboxyl group (-COOH), making it an acidic amino acid.
- Chemical Properties: Due to its extra amino group, Lysine is positively charged at physiological pH and has a high isoelectric point. In contrast, Aspartic acid is negatively charged at physiological pH and has a low isoelectric point.
7. How does Lysine participate in the formation of a peptide bond?
Lysine participates in forming a peptide bond through a condensation reaction. The α-carboxyl group (-COOH) of one amino acid (e.g., Lysine) reacts with the α-amino group (-NH₂) of another amino acid. This reaction eliminates a molecule of water (H₂O) and forms a covalent bond known as a peptide linkage (-CONH-). This process is fundamental to creating the primary structure of all proteins.
8. What are some common dietary sources that provide the essential amino acid Lysine?
Since the body cannot produce Lysine, it must be consumed through food. High-quality protein sources are typically rich in Lysine. Common examples include:
- Animal products like meat, poultry, fish, and eggs.
- Dairy products such as milk, yogurt, and cheese.
- Legumes, especially soybeans and lentils.
- Nuts and seeds like pumpkin seeds.
