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Why can't the human body synthesize lysine on its own? What is the biological mystery behind this?
Lysine, represented by the symbol Lys or K, is an α-amino acid that is widely involved in the synthesis of various proteins. As a basic amino acid, lysine has an α-amino group and an α-carboxyl group and has a side chain, which makes it positively charged in aqueous solution. Although lysine plays an extremely important role in organisms, humans are unable to synthesize this amino acid on their own. The biological reasons behind this are worth exploring.
Lysine is an essential amino acid for the human body and must be obtained through diet.
Like most other amino acids, the α-carbon atom of L-lysine is a chiral center, which means it exists in different forms. However, the human body can only use it in its biologically active form and cannot obtain it through internal synthesis. This phenomenon raises a question: Why did the human body fail to develop the ability to synthesize lysine during evolution?
Lysine metabolic pathway
In nature, there are two major lysine biosynthesis pathways: the diametropyline pathway (DAP) and the α-aminoglutarate pathway (AAA). These pathways involve different enzymes and substrates, some of which are found in bacteria and plants. The existence of these two pathways shows how organisms rely on their own metabolic pathways to make lysine, while humans can only rely on dietary supply.
The synthesis process of lysine regulates its activity and the body's requirement for this amino acid.
For example, the DAP pathway occurs primarily in prokaryotes and plants, converting other compounds into lysine through enzymatic reactions. Meanwhile, the AAA pathway is more common in certain yeasts and fungi. The complex metabolic mechanisms underlying these pathways are crucial to understanding how lysine is obtained.
Biological functions of lysine
As an essential amino acid, lysine has many functions in the human body, the most important of which is its involvement in protein synthesis. It not only contributes to the stability of the skeleton structure, but also plays a key role in the cross-linking process of collagen. In addition, lysine affects the uptake of minerals, the metabolism of fatty acids, and the interaction with other molecules in the environment.
Lysine deficiency may lead to a variety of diseases, such as anemia and fatty acid metabolism disorders.
It is worth noting that insufficient lysine intake may lead to protein-energy deficiency and affect various body functions. Therefore, the supply of lysine is not only important, but must be maintained within a normal range. Excessive intake can also cause health problems, such as nervous system disorders.
Dietary sources of lysine
Since the human body cannot synthesize lysine, a reasonable diet becomes the main way to obtain lysine. Foods rich in lysine include red meat, poultry, fish, eggs and some beans. In contrast, many grains are relatively low in lysine, which requires vegetarians to pay special attention to their lysine intake in their diet.
Lysine deficiency is common in non-Western societies and can cause a variety of health problems.
Currently, scientists are also conducting research on genetic modification in order to increase the lysine content of plants. This shows that biological issues related to lysine have a profound impact on both agriculture and human nutrition.
SummaryLysine is an essential amino acid for the human body, and the lack of its synthesis makes humans rely on diet to obtain this important nutrient. Further exploration of the lack of lysine in the human body and its long-term impact on health also raises questions about genetic modification technology. We can't help but ask, how can future science balance increasing lysine supply while ensuring food safety and environmental sustainability?
