Lanthionine is a nonproteinogenic

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

with the chemical formula (HOOC-CH(NH₂)-CH₂-S-CH₂-CH(NH₂)-COOH). It is typically formed by a

cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, sometime ...

residue and a dehydrated

serine Serine (symbol Ser or S) is an α-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated − form under biological conditions), a carboxyl group (which is in the deprotonated − form un ...

residue. Despite its name, lanthionine does not contain the element

lanthanum Lanthanum is a chemical element with the symbol La and atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lant ...

Background

In 1941, lanthionine was first isolated by treating

wool Wool is the textile fibre obtained from sheep and other mammals, especially goats, rabbits, and camelids. The term may also refer to inorganic materials, such as mineral wool and glass wool, that have properties similar to animal wool. As ...

with

sodium carbonate Sodium carbonate, , (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions ...

. It was found to be a sulfur-containing amino acid; accordingly it was given the name lanthionine ool (Latin: ''Lana''), sulfur (Greek: ''theîon'') Lanthionine was first synthesized by alkylation of

with β- chloroalanine. Lanthionines are found widely in nature. They have been isolated from human hair, lactalbumin, and feathers. Lanthionines have also been found in bacterial cell walls and are the components of a group of gene-encoded

peptide Peptides (, ) are short chains of amino acids linked by peptide bonds. Long chains of amino acids are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. A ...

antibiotics called

lantibiotics Lantibiotics are a class of polycyclic peptide antibiotics that contain the characteristic thioether amino acids lanthionine or methyllanthionine, as well as the Saturated and unsaturated compounds, unsaturated amino acids dehydroalanine, and 2-Am ...

, which includes

nisin Nisin is a polycyclic antibacterial peptide produced by the bacterium ''Lactococcus lactis'' that is used as a food preservative. It has 34 amino acid residues, including the uncommon amino acids lanthionine (Lan), methyllanthionine (MeLan), di ...

(a food preservative), subtilin, epidermin (effective against '' Staphylococcus'' and ''

Streptococcus ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occurs ...

''), and ancovenin (an enzyme inhibitor).Shao, H.; Wang, S. H. H.; Lee, C.-W.; Ösapay, G.; Goodman, M. (1995) A Facile Synthesis of Orthogonally Protected Stereoisomeric Lanthionines by Regioselective Ring Opening of Serine β-Lactone Derivatives. ''

Journal of Organic Chemistry ''The Journal of Organic Chemistry'', colloquially known as ''JOC'', is a peer-reviewed scientific journal for original contributions of fundamental research in all branches of theory and practice in organic and bioorganic chemistry. It is publi ...

'', ''60'', 2956-2957.

Preparation

A variety of syntheses of lanthionine have been published including sulfur extrusion from cystine, ring opening of serine β-lactone, and hetero-conjugate addition of cysteine to

dehydroalanine Dehydroalanine (Cα,β-didehydroalanine, α,β-di-dehydroalanine, 2-aminoacrylate, or 2,3-didehydroalanine) is a dehydroamino acid. It does not exist in its free form, but it occurs naturally as a residue found in peptides of microbial origin. As ...

. The sulfur extrusion method is, however, the only pathway for lanthionine that has been employed in the total synthesis of a lantibiotic. Biosynthesis of the lanthionine bridge in peptidic natural products can be accomplished through a number of different pathways. For example, the lanthionine bridges in the antibiotic

are the result of a dedicated dehydratase (NisB) and a dedicated cyclase (NisC).

References

Sulfur amino acids Thioethers Non-proteinogenic amino acids {{Non-proteinogenic amino acids