Lysine is an α-amino acid that is used in the biosynthesis of proteins.
It contains an α-amino group, an α-carboxylic acid group, and a side chain lysyl , classifying it as a basic, charged aliphatic amino acid.
It is encoded by the codons AAA and AAG.
Humans cannot synthesize lysine.
It is essential in humans and must be obtained from the diet.
Lysine plays several roles: most importantly proteinogenesis, crosslinking of collagen polypeptides, uptake of essential mineral nutrients, and in the production of carnitine, which is key in fatty acid metabolism.
It is also often involved in histone modifications.
Lysine affects the epigenome.
Lysine deficiency can lead to several disease states including: defective connective tissues, impaired fatty acid metabolism, anemia, and systemic protein-energy deficit.
An overabundance of lysine, caused by ineffective catabolism, can cause severe neurological disorders.
Lysine biosynthesis pathways. Two pathways are responsible for the de novo biosynthesis of L-lysine: The diaminopimelate (DAP) pathway, the α-aminoadipate (AAA) pathway
The saccharopine pathway is the most prominent pathway for the catabolism of lysine.
Catabolism of lysine is initiated from the uptake of dietary lysine or from the breakdown of intracellular protein.
Catabolism controls the intracellular concentration of free lysine and maintains a steady-state to prevent the toxic effects of excessive free lysine.
Lysine catabolism commonly uses is the saccharopine pathway, which primarily takes place in the liver and specifically within the mitochondria.
Lysine is an essential amino acid.
Nutritional requirements varies from ~60 mg·kg/d−1 in infancy to ~30 mg·kg/d in adults.
The nutritional requirement is met with the intake of lysine from meat and vegetable sources well in excess of the recommended requirement.
In vegetarian diets, the intake of lysine is less due to the limited quantity of lysine in cereal crops compared to meat sources.
Good sources of lysine are high-protein foods such as eggs, meat;
red meat, lamb, pork, and poultry, soy, beans and peas, cheese, particularly Parmesan, and certain fish; such as cod and sardines.
Lysine is the limiting amino acid in most cereal grains, but is plentiful in most pulses ((legumes)).
A vegetarian or low animal protein diet can be adequate for protein, including lysine, if it includes both cereal grains and legumes.
A food is considered to have sufficient lysine if it has at least 5.1% lysine.
As a dietary supplement L-lysine HCl provides 80.03% L-lysine.
1 g of L-lysine is contained in 1.25 g of L-lysine HCl.
Foods containing significant proportions of lysine:
Fish 9.19%
Beef, ground, 90% lean/10%
Chicken 8.11%
Milk, non-fat 7.48%
Soybean, mature seeds, raw 7.42%
Egg, whole, raw 7.27%
Pea, split, mature seeds, raw 7.22%
Lentil, pink, raw 6.97%
Kidney bean, mature seeds, raw 6.87%
Chickpea, (garbanzo beans, Bengal gram), mature seeds, raw 6.69%
Navy bean, mature seeds, raw 5.73%
The most common role for lysine is proteinogenesis.
It plays an important role in protein structure.
It is considered somewhat amphipathic.
Covalent histone modifications have downstream effects on gene regulation, in which genes can be activated or repressed.
Lysine plays a key role in other biological processes: structural proteins of connective tissues, calcium homeostasis, and fatty acid metabolism.
Lysine is involved in the crosslinking between the three helical polypeptides in collagen, resulting in its stability and tensile strength.
Lysine is suspected to be involved in calcium intestinal absorption and renal retention, and may play a role in calcium homeostasis.
It is a precursor for carnitine, which transports fatty acids to mitochondria, where they can be oxidized for the release of energy.
However, the primary source of carnitine is through dietary sources, rather than through lysine conversion.
Diseases related to lysine are related to
its downstream processing with the incorporation into proteins or modification into alternative biomolecules.
A lack of lysine and hydroxylysine involved in the crosslinking of collagen peptides has been linked to a disease state of the connective tissue.
Carnitine is a key lysine-derived metabolite involved in fatty acid metabolism.
A diet lacking sufficient carnitine and lysine can lead to decreased carnitine levels, which can have significant effects on health.
Lysine has also been shown to play a role in anemia.
Lysine has an effect on the uptake of iron and, subsequently, the concentration of ferritin in blood plasma.
Lysine deficiency is seen in non-western societies.
Lysine deficiency manifests as protein-malnutrition, with systemic effects on the health of the individual.
There are hereditary genetic mutations
that involves enzymes responsible for lysine catabolism.
With mutations that impair lysine catabolism, the amino acid accumulates in plasma and patients develop hyperlysinaemia.
Hyperlysinaemia can lead to neurological disabilities, including epilepsy, ataxia, spasticity, and psychomotor impairment, although this is subject to debate.
Mutations in genes related to lysine metabolism have been implicated in several disease states, including pyridoxine-dependent epilepsia via the ALDH7A1 gene, α-ketoadipic and α-aminoadipic aciduria viA DHTKD1 gene, and glutaric aciduria type 1 via GCDH gene.
Hyperlysinuria is associated with high amounts of lysine in the urine.
Hyperlysinuria is often due to a metabolic disease in which a protein involved in the breakdown of lysine is non functional due to a genetic mutation, or it may also occur due to a failure of renal tubular transport.
Lysine is an important additive to animal feed because it is a limiting amino acid when optimizing the growth of certain animals such as pigs and chickens.
Lysine supplementation allows for the use of lower-cost plant protein, while maintaining high growth rates, and limiting the pollution from nitrogen excretion.
Lysine is often involved in histone modifications, and thus, impacts the epigenome.
Saccharopine lysine catabolism pathway is the most prominent pathway for the catabolism of lysine.
Catabolism of lysine is initiated from the uptake of dietary lysine or from the breakdown of intracellular protein.
Catabolism controls the intracellular concentration of free lysine and maintains a steady-state to prevent the toxic effects of excessive free lysine.
Lysine catabolism occurs most commonly in the saccharopine pathway, which primarily takes place in the liver,
specifically within the mitochondria.
The lysine nutritional requirements varies from ~60 mg·kg/d in infancy to ~30 mg·kg/d in adults.
This requirement is met
with the intake of lysine from meat and vegetable sources which are well in excess of the recommended requirement.
In vegetarian diets, the intake of lysine is less due to the limiting quantity of lysine in cereal crops.
Good sources of lysine are high-protein foods: eggs, meat, especifically red meat, lamb, pork, and poultry, soy, beans and peas, cheese and certain fish as cod and sardines.
It is found in the smallest quantity in most cereal grains, but is plentiful in most legumes.
A food is considered to have sufficient lysine if it has at least 51 mg of lysine per gram of protein (5.1% lysine).
L-lysine HCl is used as a dietary supplement, providing 80.03% L-lysine.[
Food Lysine (% of protein)
Fish 9.19%
Beef, ground, 90% lean/10% fat, cooked 8.31%
Chicken, roasting, meat and skin,
cooked, roasted 8.11%
Azuki bean (adzuki beans), mature seeds, raw 7.53%
Milk, non-fat 7.48%
Soybean, mature seeds, raw 7.42%
Egg, whole, raw 7.27%
Pea, split, mature seeds, raw 7.22%
Lentil, pink, raw 6.97%
Kidney bean, mature seeds, raw 6.87%
Chickpea, (garbanzo beans, Bengal gram), mature seeds, raw 6.69%
Navy bean, mature seeds, raw 5.73%
Its most common role for lysine is proteinogenesis, and protein structure.
A second major role of lysine is in epigenetic regulation by means of histone modification, which have downstream effects on gene regulation, in which genes can be activated or repressed.
Lysine plays a key role in other biological processes including; structural proteins of connective tissues, calcium homeostasis, and fatty acid metabolism.
It is involved in the crosslinking between helical polypeptides in collagen, resulting in its stability and tensile strength.
Opsins like rhodopsin and the visual opsins, encoded by the genes OPN1SW, OPN1MW, and OPN1LW, forms a Schiff base with a conserved lysine residue, and interacts with light causing signal transduction in color vision.
Lysine related diseases are a result of the downstream processing of lysine, incorporating it into proteins or modification into alternative biomolecules.
A lack of lysine and hydroxylysine involved in the crosslinking of collagen peptides has been linked to a diseased state of connective tissues.
Carnitine is a key lysine-derived metabolite involved in fatty acid metabolism.
A diet lacking sufficient carnitine and lysine can lead to decreased carnitine levels, which can have adverse effects on health.
Lysine effects on the uptake of iron and, subsequently, the concentration of ferritin in blood plasma.
Lysine deficiency is seen in non-western societies as protein-energy malnutrition.
A hereditary genetic disease that involves mutations in the enzymes of responsible for lysine catabolism, the bifunctional AASS enzyme of the saccharopine pathway.
With a lack of lysine catabolism, the amino acid accumulates in plasma and patients develop hyperlysinaemia.
Hyperlysinaemia can present as asymptomatic to severe neurological disabilities, including epilepsy, ataxia, spasticity, and psychomotor impairment.
Mutations in genes related to lysine metabolism have been implicated in several disease states, including pyridoxine-dependent epilepsia (ALDH7A1 gene), α-ketoadipic and α-aminoadipic aciduria (DHTKD1 gene), and glutaric aciduria type 1 (GCDH gene).
Hyperlysinuria is marked by high amounts of lysine in the urine.
Hyperlysinuria may occur due to a failure of renal tubular transport.
Lysine production for animal feed is a major global industry.