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Lysine
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Lysine (abbreviated as Lys or K) is an a-amino acid with the chemical formula HO2CCH(NH2)(CH2)4NH2. This amino acid is an essential amino acid, which means that humans cannot synthesize it. Its codons are AAA and AAG.
Lysine is a base, as are arginine and histidine. The e-amino group often participates in hydrogen bonding and as a general base in catalysis. Common posttranslational modifications include methylation of the e-amino group, giving methyl-, dimethyl-, and trimethyllysine.
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Encyclopedia
Lysine (abbreviated as Lys or K) is an a-amino acid with the chemical formula HO2CCH(NH2)(CH2)4NH2. This amino acid is an essential amino acid, which means that humans cannot synthesize it. Its codons are AAA and AAG.
Lysine is a base, as are arginine and histidine. The e-amino group often participates in hydrogen bonding and as a general base in catalysis. Common posttranslational modifications include methylation of the e-amino group, giving methyl-, dimethyl-, and trimethyllysine. The latter occurs in calmodulin. Other posttranslational modifications at lysine residues include acetylation and ubiquitination. Collagen contains hydroxylysine which is derived from lysine by lysyl hydroxylase. O-Glycosylation of lysine residues in the endoplasmic reticulum or Golgi apparatus is used to mark certain proteins for secretion from the cell.
Biosynthesis
As an essential amino acid, lysine is not synthesized in animals, hence it must be ingested as lysine or lysine-containing proteins. In plants and bacteria, it is synthesized from aspartic acid, which is first converted to ß-aspartyl-semialdehyde. Cyclization gives dihydropicolinate, which is reduced to ?1-piperidine-2,6-dicarboxylate. Ring-opening of this heterocycle gives a series of derivatives of pimelic acid, ultimately affording lysine. Enzymes involved in this biosynthesis include:
- Aspartokinase
- ß-aspartate semialdehyde dehydrogenase
- Dihydropicolinate synthase
- ?1-piperidine-2,6-dicarboxylate dehydrogenase
- N-succinyl-2-amino-6ketopimelate synthase
- Succinyl diaminopimelate aminotransferase
- Succinyl diaminopimelate desuccinylase
- Diaminopimelate epimerase
- Diaminopimelate decarboxylase
Metabolism
Lysine is metabolised in mammals to give acetyl-CoA, via an initial transamination with a-ketoglutarate. The bacterial degradation of lysine yields cadaverine by decarboxylation.
Allysine is a derivative of lysine, used in the production of elastin and collagen. It is produced by the actions of the enzyme lysyl oxidase on lysine in the extracellular matrix and is essential in the crosslink formation that stabilizes collagen and elastin.
Synthesis
Synthetic, racemic lysine has long been known. A practical synthesis starts from caprolactam.
Dietary sources
The human nutritional requirement is 1–1.5 g daily. It is the limiting amino acid (the essential amino acid found in the smallest quantity in the particular foodstuff) in all cereal grains, but is plentiful in all pulses (legumes). Plants that contain significant amounts of lysine include:
- Buffalo Gourd (10,130–33,000 ppm) in seed
- Berro, Watercress (1,340–26,800 ppm) in herb.
- Soybean (24,290–26,560 ppm) in seed.
- Carob, Locust Bean, St.John's-Bread (26,320 ppm) in seed;
- Common Bean (Black Bean, Dwarf Bean, Field Bean, Flageolet Bean, French Bean, Garden Bean, Green Bean, Haricot, Haricot Bean, Haricot Vert, Kidney Bean, Navy Bean, Pop Bean, Popping Bean, Snap Bean, String Bean, Wax Bean) (2,390–25,700 ppm) in sprout seedling;
- Ben Nut, Benzolive Tree, Jacinto (Sp.), Moringa (aka Drumstick Tree, Horseradish Tree, Ben Oil Tree), West Indian Ben (5,370–25,165 ppm) in shoot.
- Lentil (7,120–23,735 ppm) in sprout seedling.
- Asparagus Pea, Winged Bean (aka Goa Bean) (21,360–23,304 ppm) in seed.
- Fat Hen (3,540–22,550 ppm) in seed.
- Lentil (19,570–22,035 ppm) in seed.
- White Lupin (19,330–21,585 ppm) in seed.
- Black Caraway, Black Cumin, Fennel-Flower, Nutmeg-Flower, Roman Coriander (16,200–20,700 ppm) in seed.
- Spinach (1,740–20,664 ppm).
- Amaranth, Quinoa
- Kasha
Good sources of lysine are foods rich in protein including meat (specifically red meat, lamb, pork, and poultry), cheese (particularly Parmesan), certain fish (such as cod and sardines), and eggs.
Properties
L-Lysine is a necessary building block for all protein in the body. L-Lysine plays a major role in calcium absorption; building muscle protein; recovering from surgery or sports injuries; and the body's production of hormones, enzymes, and antibodies.
Modifications
Lysine can be modified through acetylation, methylation, ubiquitination, sumoylation, neddylation, biotinylation and carboxylation which tends to modify the function of the protein of which the modified lysine residue(s) are a part.
Clinical significance
It has been suggested that lysine may be beneficial for those with herpes simplex infections. However, more research is needed to fully substantiate this claim. For more information, refer to Herpes simplex - Lysine.
There are Lysine conjugates that show promise in the treatment of cancer, by causing cancerous cells to destroy themselves when the drug is combined with the use of phototherapy, while leaving non-cancerous cells unharmed.
In popular culture
The 1993 film Jurassic Park, which is based on the 1990 Michael Crichton novel Jurassic Park, features dinosaurs that were genetically altered so they could not produce lysine. This was supposed to prevent the cloned dinosaurs from leaving the park, forcing them to depend on lysine supplements provided by the park's veterinary staff. Most vertebrates cannot produce lysine by default (it is an essential amino acid).
In 1996, lysine became the focus of the largest successful conviction of a price fixing case in United States history. Archer-Daniels-Midland paid a fine of $100 million dollars, and three of its executives were convicted and served prison time. Also found guilty in the price fixing case were two Japanese firms (Ajinomoto, Kyowa Hakko) and a South Korean firm (Sewon). Secret video recordings of the conspirators fixing lysine's price can be found online or by requesting the video from the U.S. Department of Justice, Antitrust Division. This case served as the basis of the movie The Informant, and a book of the same title.
The 2002 Max Tundra single "Lysine" (featuring Becky Jacobs) is a tribute to the advantages of lysine.
Linus Pauling believed people with existing atherosclerotic plaque can benefit from vitamin c and the amino acid lysine. Pauling filmed a video lecture in which he recommended that heart patients take between 2,000 and 6,000 mg of lysine daily with their vitamin C (more if serum Lp(a) is elevated).
In the sitcom The Big Bang Theory, the episode The Friendship Algorythm (air date 1/19/2009), it is revealed that Sheldon's favorite amino acid is Lysine. Although Raj had thought it was l-glutamine.
See also
Sources
- Much of the information in this article has been translated from German Wikipedia.
External links
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