Wikipedia:  

L-Cysteine

Cysteine, L-; alpha-Amino-beta-mercaptopropionic acid, L-; Cysteine; Thioserine; L-CYSTEINE; alpha-Amino-beta-mercaptopropanoic acid, L-; (R)-2-Amino-3-mercaptopropionic acid; 2-Amino-3-mercaptopropionic acid; L-2-Amino-3-mercaptopropanoic acid; L-Alanine, 3-mercapto-; Cisteinum [Latin]
Molecular Formula
C3 H7 N O2 S
Natural Isotopic Abundance Mass
121.1581800000
Mono-Isotopic Molecular Masses
C12N14:   121.019749164
C13N14:   124.029813677
C12N15:   122.016784057
C13N15:   125.0268485707
L-Cysteine image
L-Cysteine
InCHi String:
InChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m0/s1

isomeric SMILES:
C([C@@H](C(=O)O)N)S
canonical SMILES:
C(C(C(=O)O)N)S


IUPAC
(2R)-2-amino-3-sulfanyl-propanoic acid

IUPAC traditional: IUPAC cas
(2R)-2-amino-3-mercapto-propanoic acid



PubChem Substance (SID):   85164882   148667   3397
PubChem Compound (CID):   5862
KEGG: Compound ID   C00097
CAS Registry IDs:   4371-52-2   52-90-4   7048-04-6
PDB Chemical Component   n/a
Miscellaneous Databases and IDs:   CHEBI 17561   FEMA No. 3263   CCRIS 912   NSC 8746   EINECS 200-158-2   HSDB 2109

Reference data were obtained primarily from the PubChem database.

Three dimensional molecular rendering uses Jmol.