Lysiinien

Lysiinien, commonly referred to in English as lysines, are essential amino acids required for human growth and tissue maintenance. The best known member is L-lysine, which exists primarily as the L-enantiomer used in human metabolism. Humans cannot synthesize lysine and must obtain it from diet. Lysine residues in proteins contribute to structure through ionic interactions and serve as sites for post-translational modifications; lysine is also a precursor in the synthesis of carnitine, a molecule involved in fatty acid transport, and plays a key role in collagen cross-linking via lysyl oxidase.

Lysiinien are abundant in animal products such as meat, fish, dairy, and eggs, and are present in plant sources like legumes, soy, quinoa, and certain seeds. However, cereals are relatively low in lysine, which makes lysine the limiting amino acid in many plant-based diets; combining complementary plant proteins can improve overall lysine intake. Daily lysine requirements are met by a balanced diet; nutrition guidelines outline recommended intakes for populations and age groups.

In biochemistry, lysine residues in histones and other proteins undergo acetylation, methylation, and ubiquitination, influencing gene expression and protein function. Deficiency is rare but can occur in severely restricted diets, leading to poor growth, anemia, and immune dysfunction. Excess lysine from supplements is generally well tolerated but can cause gastrointestinal upset in some individuals.

See also: essential amino acids; protein synthesis; lysyl oxidase; carnitine; histone modification.