Why Is L Methionine Essential for Your Body?
Human beings possess an essential amino acid known as L Methionine. This compound plays a vital part in the health and metabolism of multiple species and also in human beings. Moreover, it is a crucial bit of angiogenesis (development of new blood vessels).
Methionine Structure
Between two amino acids, Methionine contains sulphur while the other one is cysteine. Generally, every amino acid holds a similar structure that is an amino group connected to one hydrogen, one side is a chain group and the other is a carboxyl group. Moreover, Methionine's chemical formula is C5H11NO2S, and its side chain is C2H7S.
Following is a diagram that shows Methionine structure
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Dietary Sources of L –Methionine
High concentrations of L-methionine are present in meat, eggs, Brazil nuts and sesame seeds. Notably, it is also available in some seeds of plants and cereals. However, maximum vegetables and fruits hold low levels of L-Methionine.
Maximum legumes have a low amount of protein content, and hence they are low in L-Methionine. Moreover, the protein sources which do not have enough of L-Methionine are not counted as complete proteins. Due to this reason, sometimes pet foods are mixed with racemic Methionine.
Furthermore, individuals must not overcook or excessively boil food products containing L – methionine. It may damage the amino acid structure as they are hugely soluble.
A Tabular Representation Showing Sources of Food Containing Methionine.
Effectiveness Of L Methionine
The most important use of Methionine is for the treatment of acetaminophen poisoning. Although there is a lack of evidence, this amino acid may also be useful for the following diseases:
Breast Cancer
Humans who intake high quantities of Methionine are less prone to breast cancer.
Parkinson's Disease
Some studies suggest that if individuals take L-methionine via food for at least six months, they may experience improvement in Parkinson's disease symptoms like tremor, rigidity and incapability of controlling movements.
Neural Tube Defects at the Time of Birth
Females who eat more amounts of L-methionine during their pregnancy may have a reduced risk of neural tube issues.
Apart from the mentioned diseases, Methionine can improve several other health conditions like herpes simplex virus (HSV), pancreatitis, asthma, schizophrenia, depression, liver function, shingles, human papillomavirus, allergies, urinary tract infections, etc.
Moreover, there are other Methionine uses as well. It can be used as an additive to dogs as it assists in lessening the growth of kidney stones in them. Also, it acts as a pesticide to fight against caterpillars (giant swallowtail) which damage orange crops.
Impact On Health
Reduction of L-methionine is related to hair greying. Due to loss of this amino acid, hydrogen peroxide gets built up in follicles of hair which results in lack of tyrosinase effect. Hence, it further leads to hair discolouration.
On the other hand, large doses of Methionine may affect the human brain and cause heart diseases. Also, it can enhance the development of a few tumours. Hence, Methionine must not be used by self-medication.
Do It Yourself
1. L – methionine is essential for growth of _________ ________ in the human body.
2. High levels of methionine is available in _________, _________, _________ and _________.
3. L – methionine is vastly used for the treatment of __________ __________.
4. The chemical formula of methionine is _________.
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FAQs on L Methionine: Structure, Functions & Sources
1. What is L-methionine and why is it classified as an essential amino acid?
L-methionine is one of the twenty standard amino acids that serve as the building blocks of proteins. It is classified as an essential amino acid because the human body cannot synthesise it on its own. Therefore, it must be obtained from dietary sources to meet the body's physiological needs for protein synthesis and other metabolic functions.
2. What are the primary biological functions of L-methionine in the body?
L-methionine plays several crucial roles in the body. Its main functions include:
- Protein Synthesis: It serves as a fundamental component for building various proteins and is the initiator amino acid in the translation process in eukaryotes.
- Sulfur Source: It is a principal supplier of sulfur, which is vital for the synthesis of other important molecules like cysteine, taurine, and the antioxidant glutathione.
- Methyl Group Donor: It is a precursor to S-adenosylmethionine (SAM), the primary methyl group donor in the body, which is essential for numerous reactions, including DNA methylation and neurotransmitter synthesis.
- Metabolism: It helps in fat metabolism by preventing excess fat accumulation in the liver.
3. How does the sulfur atom in L-methionine's structure contribute to its unique biological roles?
The sulfur atom in L-methionine's side chain (a thioether group) is central to its functionality. This feature makes it chemically unique among the essential amino acids. It allows methionine to be a versatile precursor for other sulfur-containing compounds like cysteine. Furthermore, the sulfur atom in the derivative S-adenosylmethionine (SAM) is key to its role as a methyl donor, enabling the transfer of a methyl group, which is a critical step in countless biochemical pathways.
4. As the initiator amino acid for protein synthesis in eukaryotes, what is the significance of L-methionine?
The significance of L-methionine as the initiator amino acid is that every protein synthesis process in eukaryotes begins with it. The start codon on messenger RNA (mRNA), which is typically AUG, codes for methionine. This means that a transfer RNA (tRNA) carrying methionine is the first to bind to the ribosome-mRNA complex, initiating the elongation of the polypeptide chain. While this initial methionine is often removed from the final protein, its role as the 'start signal' is fundamental to the entire process of translation.
5. What are some common dietary sources of the essential amino acid L-methionine?
Since L-methionine is an essential amino acid, it must be obtained through diet. Good sources are typically protein-rich foods. Examples include:
- Animal-based sources: Meat, fish (like tuna), eggs, and dairy products (like milk, cheese, and yoghurt).
- Plant-based sources: Tofu and other soy products, nuts (especially Brazil nuts), seeds (like sesame and sunflower seeds), and whole grains like oats and quinoa.
6. What is the difference between L-methionine and D-methionine, and are both biologically useful?
L-methionine and D-methionine are stereoisomers or enantiomers, meaning they are mirror images of each other. The primary difference lies in their three-dimensional structure. In biological systems, particularly in humans, enzymes are highly specific and are configured to recognise and use the L-form of amino acids for protein synthesis. While the body can convert some D-methionine into L-methionine, the L-form is the directly usable and more biologically active version for building proteins.
7. How is L-methionine chemically classified among the amino acids?
Based on its chemical properties, L-methionine is classified as a nonpolar, aliphatic amino acid. The 'nonpolar' classification is due to its side chain, which contains a thioether group (C–S–C) and does not have a charge at physiological pH, making it hydrophobic. It is also one of the two sulfur-containing amino acids, the other being cysteine.
