Homocysteine thiolactone

Homocysteine thiolactone
Names
	IUPAC name (3S)-3-aminothiolan-2-one
Identifiers
CAS Number	2338-04-7;
3D model (JSmol)	Interactive image;
Beilstein Reference	80591
ChEBI	CHEBI:60315;
ChEMBL	ChEMBL4078313;
ChemSpider	118559;
PubChem CID	134505;
	InChI InChI=1S/C4H7NOS/c5-3-1-2-7-4(3)6/h3H,1-2,5H2/t3-/m0/s1 Key: KIWQWJKWBHZMDT-VKHMYHEASA-N;
	SMILES C1CSC(=O)[C@H]1N;
Properties
Chemical formula	C4H7NOS
Molar mass	117.17 g·mol−1
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Homocysteine thiolactone (HTL) is an organosulfur compound with the formula H₂NCHC(O)SCH₂CH₂. It is the thiolactone (intramolecular thioester) of homocysteine. It is produced by methionyl-tRNA synthetase in an error-editing reaction that prevents translational incorporation of homocysteine into proteins.

HTL can damage proteins through "homocysteinylation" of protein lysine residues. HTL has been reported to form isopeptide bonds with lysine residues in substrate proteins, a post-translational modification known as N-homocysteinylation (N-Hcy). This causes protein damage via a thiyl radical mechanism. The drugs citiolone and erdosteine are modified versions of homocysteine thiolactone.

When N-Hcy binds α-syn, it exacerbates α-syn aggregation, neurotoxicity, and dopaminergic neuronal degeneration. It also damages the protein DJ-1, contributing to Parkinson's disease.