CAS 52-90-4PubChem CID 5862
L-(+)-Cysteine
L-cysteine is an optically active form of cysteine having L-configuration. It has a role as a flour treatment agent, an EC 4.3.1.3 (histidine ammonia-lyase) inhibitor and a human metabolite. It is a cysteine, a L-alpha-amino acid, a serine family amino acid and a proteinogenic amino acid. It is a conjugate base of a L-cysteinium. It is a conjugate acid of a L-cysteinate(1-). It is an enantiomer of a D-cysteine. It is a tautomer of a L-cysteine zwitterion. — ChEBI
- IUPAC name
- (2R)-2-amino-3-sulfanylpropanoic acid
- Molecular formula
- C3H7NO2S
- Molecular weight
- 121.16 g/mol
- Exact mass
- 121.01974964 Da
- XLogP3
- -2.5
- Topological polar surface area
- 64.3 Ų
- Hydrogen-bond donors
- 3
- Hydrogen-bond acceptors
- 4
- Covalent units
- 1
- Defined stereocentres
- 1
Also known as
L-cysteinecysteineCystein(R)-2-Amino-3-mercaptopropanoic acidThioserineHalf-cystinebeta-MercaptoalanineL-Cystein
16 more reported names
CysteinumL-CyscisteinaHalf cystine2-Amino-3-mercaptopropionic acidL-Alanine, 3-mercapto-FREE CYSTEINECisteinumFEMA No. 3263Cisteinum [Latin]NSC-8746alpha-Amino-beta-thiolpropionic acidL-2-Amino-3-mercaptopropionic acidbeta-Mercaptoalanine, L-(2R)-2-amino-3-mercaptopropanoic acidL Cysteine
External database identifiers
Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.