Lysine is one of the 20 amino acids normally found in proteins. With its 4-aminobutyl side-chain, it is classified as a basic amino acid, along with arginine and histidine. It is an essential amino acid, and the human nutritional requirement is 1–1.5 g daily. A deficiency in lysine can result in a deficiency in niacin (which is a B Vitamin). This can cause the disease pellagra. Lysine can also be used as a nutritional supplement to help against herpes.
Lysine is the limiting amino acid in all cereal grains, but is plentiful in all pulses (legumes). Fish are also quite rich in lysine. 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, Drumstick Tree, Horseradish Tree, Jacinto (Sp.), Moringa, West Indian Ben (5,370–25,165 ppm) in shoot.
- Lentil (7,120–23,735 ppm) in sprout seedling.
- Asparagus Pea, Goa Bean, Winged 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) in slant.
Lysine can undergo posttranslational modification in protein molecules, often by methylation? or acetylation. Collagen contains hydroxylysine which is derived from lysine. O-Glycosylation? of lysine residues in the endoplasmic reticulum or Golgi apparatus is used to mark certain proteins for secretion from the cell.
Lysine is metabolised in mammals to give Acetyl-CoA, via an initial transamination with α-ketoglutarate. The bacterial degradation of lysine yields cadaverine? by decarboxylation.
Some individuals have found that taking lysine supplements may reduce the frequency of canker sores and cold sores, the latter being derived from an infection related to the Herpes virus.