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Pyrrolysine

Pyrrolysine
Pyrrolysine.svg
Pyrrolysine-3D-balls.png
Names
IUPAC name
N6-{[(2R,3R)-3-methyl-3,4-dihydro-2H-pyrrol-2-yl]carbonyl}-L-lysine
Identifiers
448235-52-7 N
3D model (Jmol) Interactive image
ChEBI CHEBI:21860 N
ChemSpider 4574156 YesY
KEGG C16138 YesY
PubChem 5460671
Properties
C12H21N3O3
Molar mass 255.313 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Pyrrolysine (abbreviated as Pyl or O; encoded by the 'amber' stop codon UAG) is an ɑ-amino acid that is used in the biosynthesis of proteins in some methanogenic archaea and bacterium; it is not present in humans. It contains an α-amino group (which is in the protonated –+NH3 form under biological conditions), a carboxylic acid group (which is in the deprotonated –COO form under biological conditions). Its pyrroline side-chain is similar to that of lysine in being basic and positively charged at neutral pH.

Nearly all proteins are made using only 20 standard amino acid building blocks. Two unusual genetically-encoded amino acids are selenocysteine and pyrrolysine. Pyrrolysine was discovered in 2002 at the active site of methyl-transferase enzyme from a methane-producing archeon, Methanosarcina barkeri. This amino acid is encoded by UAG (normally a stop codon), and its synthesis and incorporation into protein is mediated via the biological machinery encoded by the pylTSBCD cluster of genes.

As determined by X-ray crystallography and MALDI mass spectrometry, pyrrolysine is made up of 4-methylpyrroline-5-carboxylate in amide linkage with the ϵN of lysine.

Pyrrolysine is synthesized in vivo by joining two molecules of L-lysine. One molecule of lysine is first converted to (3R)-3-methyl-D-ornithine, which is then ligated to a second lysine. An NH2 group is eliminated, followed by cyclization and dehydration step to yield L-pyrrolysine.


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