What is Arginine?
Arginine or L-arginine is an amino acid that is obtained by the hydrolysis of several common proteins, but specifically proteins associated with histones and protamines as they are associated with nucleic acids. The amino acid was first isolated in 1895 from an animal horn, and since then, extensive studies have shown its importance in living organisms. Arginine plays a critical role in all mammals for the synthesis of urea, it is the form in which mammals excrete nitrogen from their body. It is one of the many nonessential amino acids found in adult mammals.
Basic Introduction of Arginine
Arginine is synthesized in these species from glutamic acid without the supplement of any additional dietary sources. It is also found in poultry, red meat, fish, and other dairy products. Upon further studies, it is found that arginine also stimulates the release of insulin, growth hormone, and other important substances in the body. It breaks down during a chemical reaction and is converted into nitric oxide, which causes the blood vessels to open up broader for better blood circulation.
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Uses of Arginine
Due to this exceeding importance, arginine supplements are used for various medical treatments. Heart and blood vessel medical conditions like congestive heart failure, high blood pressure, chest pain, and coronary artery disease are treated with the help of arginine.
It is also used to treat the recurrent pain in the legs, which is caused due to blocked arteries, erectile dysfunction, decreased mental capacity usually found in elderly people, and male infertility. Doctors also use arginine supplement to treat and improve kidney function after kidney transplant surgery is performed. The kidney is particularly vulnerable and needs an extra boost to settle in and function in the new body.
Arginine also prevents the common cold and greatly improves the athletic performance of an individual. Furthermore, arginine can also be used to boost the immunity of a person and prevent digestive tract inflammation in premature individuals. Naturally, it can be concluded that L-Arginine is vital for the growth of T-cells, which are also known as white blood cells, and they play an important role in the immune response. As these amino acids play such a critical role, the lack of them in the body will disrupt organ and cellular function, leading to serious health complications.
Benefits of L-Arginine Supplements
Some of the benefits and uses of the L-Arginine supplement were briefly mentioned above. Below given is more information on the same and additional benefits of arginine amino acid.
1. Regulation of Blood Pressure
Scientific studies have shown that by taking L-arginine supplements, one can lower one diastolic and systolic blood pressure. As mentioned above, L-arginine is important for the production of nitric oxide, which is required for the blood vessels to relax. Thus regulates the blood pressure in the human body.
2. Treating Erectile Dysfunction
A 2019 review of a total of 10 studies found that taking L-arginine supplements in 1.5-5 grams of daily dosage range can considerably improve erectile dysfunction as compared to other or no treatment.
3. Preventing and Treating Preeclampsia
Preeclampsia is a dangerous blood pressure condition found in women during pregnancy. It is also characterized by high levels of protein in their urine. Studies have proven that intake of arginine in regulated dosages can treat and possibly prevent preeclampsia in pregnant women.
4. Managing Critical illness
Infections and trauma drastically affect your body and make it vulnerable. Therefore, the Arginine need in your body considerably increases because of physiologic demands. When the body cannot internally meet arginine demands, it needs to be fulfilled externally. Oral or IV arginine amino acid is usually administered to treat grave infections, such as necrotizing enterocolitis in babies, chronic diseases, sepsis, serious wounds, and burns.
Enhancement of Athletic Performance
Although the evidence is limited, it suggests that arginine supplements can improve the exercise capacity by elevating nitric oxide in the human body, enhancing blood circulation and oxygenation to the muscles. However, the intake of L-arginine to enhance athletic performance is controversial as many studies have shown that arginine supplements are not beneficial for the same.
FAQs on Arginine
1. What is arginine and what is its chemical formula as per the biomolecules chapter?
Arginine is an α-amino acid, which serves as a fundamental building block for proteins in living organisms. According to the CBSE syllabus, its chemical formula is C₆H₁₄N₄O₂. Its structure is distinguished by a side chain containing a complex guanidinium group, which gives it specific chemical properties.
2. How is arginine classified as an amino acid?
In chemistry, arginine is classified based on two key criteria:
- Based on its side chain: It is classified as a basic amino acid. This is because its side chain contains a guanidinium group, which is strongly basic and carries a positive charge at physiological pH.
- Based on nutritional needs: It is considered a non-essential amino acid for adults, meaning the human body can typically synthesise it from other compounds like glutamic acid.
3. What is the zwitterionic form of arginine?
The zwitterionic form of arginine is a molecule that has both a positive and a negative electrical charge, yet is electrically neutral overall. In an aqueous solution, its acidic carboxyl group (-COOH) donates a proton to become a negative carboxylate ion (-COO⁻), while the basic α-amino group (-NH₂) accepts a proton to become a positive ammonium ion (-NH₃⁺). This dipolar ion is known as a zwitterion, a core concept for amino acids in the NCERT curriculum.
4. What are the primary biological functions of arginine relevant to the CBSE curriculum?
Within the scope of the CBSE Chemistry syllabus, the main biological importance of arginine is its role as a precursor in the synthesis of proteins and other key molecules. Its most critical function is its participation in the urea cycle in mammals. This is the primary metabolic pathway by which the body disposes of toxic ammonia by converting it into urea for excretion.
5. Why is arginine considered a 'basic' amino acid?
Arginine is classified as a basic amino acid because its side chain contains a guanidinium group. This functional group is exceptionally basic (with a high pKa value) and readily accepts a proton at the neutral pH found in biological systems. This gives the arginine molecule an overall positive charge, as it has two basic groups (the α-amino group and the guanidinium group) and only one acidic carboxyl group, thus defining its basic nature.
6. How does the unique side chain of arginine influence the structure of proteins?
The positively charged guanidinium group in arginine's side chain is crucial for protein structure. It enables arginine to form strong ionic bonds, also known as salt bridges, with negatively charged amino acids like aspartic acid or glutamic acid. These bonds are vital for stabilising the complex three-dimensional tertiary and quaternary structures of proteins, dictating their final shape and function.
7. How does arginine differ from a neutral amino acid like glycine?
Arginine and glycine differ significantly in their structure and chemical properties:
- Side Chain: Arginine has a large, complex, and positively charged guanidinium side chain. Glycine is the simplest amino acid, with only a single hydrogen atom as its side chain.
- Chemical Nature: Arginine is basic and hydrophilic (water-loving). Glycine is neutral and nonpolar.
- Isoelectric Point (pI): Arginine has a high pI (10.76) due to its basic side chain, while glycine has a pI near neutral (5.97).
- Flexibility: Glycine's small side chain provides high flexibility to a polypeptide chain, whereas arginine's bulky side chain is more structurally constrained.
