Lysine
Essential amino acid crucial for protein synthesis and metabolism.
Lysine (symbol Lys or K; also L-lysine) is an α-amino acid that is a precursor to many proteins. It is classified as a basic, charged, aliphatic amino acid and is encoded by the codons AAA and AAG. The human body cannot synthesize lysine, making it an essential nutrient that must be obtained from the diet.
- discovered_by
- Ferdinand Heinrich Edmund Drechsel
- structure_determined_by
- Emil Fischer and Fritz Weigert
- classification
- Basic, charged, aliphatic α-amino acid
- biological_role
- Proteinogenesis, collagen crosslinking, mineral uptake, carnitine production, histone modifications
Lore & Background
The one-letter symbol K was assigned to lysine because it is the only letter not already used for another amino acid that is phonetically reminiscent of 'lysine'.
Reader's Guide
Lysine is essential in humans and must be obtained from the diet, as the human body cannot synthesize it. It plays several roles, most importantly in proteinogenesis, but also in the crosslinking of collagen polypeptides, uptake of essential mineral nutrients, and in the production of carnitine, which is key in fatty acid metabolism. Lysine is also often involved in histone modifications, impacting the epigenome. A lack of lysine can lead to defective connective tissues, impaired fatty acid metabolism, anaemia, and systemic protein-energy deficiency. Conversely, an overabundance of lysine, caused by ineffective catabolism, can cause severe neurological disorders. Two main biosynthetic pathways exist in organisms that synthesize lysine: the diaminopimelate pathway and the α-aminoadipate pathway. Catabolism primarily occurs through the saccharopine pathway, which is the reverse of the α-aminoadipate biosynthesis pathway.
Did You Know?
- The one-letter symbol K was assigned to lysine because it is the only letter not already used for another amino acid that is phonetically reminiscent of 'lysine'.
- Lysine contains an ε-ammonium group attached to the fifth carbon (the ε-carbon) from the α-carbon.
- The human body cannot synthesize lysine; it is essential and must be obtained from the diet.
Frequently Asked Questions
What is Lysine?
Lysine (symbol Lys or K) is a basic, aliphatic α-amino acid that carries a positive charge under physiological conditions. It serves as a fundamental building block for a wide variety of proteins in living cells.
Why is Lysine considered an essential amino acid?
Human cells lack the enzymatic pathway needed to build lysine from scratch, so it must be supplied through the diet. Without adequate dietary intake, protein synthesis and downstream metabolic processes are compromised.
What are Lysine's key biological roles beyond protein synthesis?
Lysine participates in collagen crosslinking, mineral uptake, carnitine biosynthesis, and histone modifications. It also acts as a precursor for several other biologically active molecules.
Who discovered Lysine and who determined its structure?
The amino acid was first isolated and identified by Ferdinand Heinrich Edmund Drechsel. Its full chemical structure was subsequently elucidated by Emil Fischer and Fritz Weigert.
Which codons encode Lysine in the genetic code?
Lysine is specified by two codons, AAA and AAG, in the standard genetic code. During translation, either of these codons directs the ribosome to attach a lysine residue to the growing polypeptide chain.
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