lysine

n. amino acid which is formed from proteins through hydrolysis

Lysine (abbreviated as Lys or K) is an α-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 ε-amino group often participates in hydrogen bonding and as a general base in catalysis. Common posttranslational modifications include methylation of the ε-amino group, giving methyl-, dimethyl-, and trimethyllysine. The latter occurs in calmodulin. Other posttranslational modifications include acetylation. 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.
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Lysine /ly·sine/ a naturally occurring, essential amino acid, necessary for optimal growth in human infants and for maintenance of nitrogen [more]Lysine - Community and Resources

Noun
1. an essential amino acid found in proteins; occurs especially in gelatin and casein
(hypernym) essential amino acid

n. lysin, antibody which causes dissolution of erythrocytes and bacteria; lysine, amino acid