Cysteine
C₃H₇NO₂S·121.159 g/mol·Amino Acids·CID 5862
Amino Acid
The only amino acid with a thiol (–SH) group. Two cysteines can form a disulfide bond (–S–S–), which stabilizes protein 3D structure. Found in keratin (hair, nails) and glutathione (the cell's primary antioxidant).
IUPAC: (2R)-2-amino-3-sulfanylpropanoic acid
Also known as: 52-90-4, cysteine, Cystein, Thioserine, Half-cystine (+14 more)
Molecular Structure
Molecular Propertiesmass · H-bonds · stereo
Molecular Weight
121.160g/mol
Exact Mass
121.019750Da
Monoisotopic Mass
121.019750Da
XLogP
-2.5
Polar Surface Area
64.3Ų
Complexity
75
Formal Charge
0
H-Bond Donors
3
H-Bond Acceptors
4
Rotatable Bonds
2
Heavy Atoms
7
Stereo Centers
1
Bond Stereo
0
Drug-Likeness (Lipinski's Rule of Five)
✓ 121.2 g/mol
MW ≤ 500
✓ -2.5
LogP ≤ 5
✓ 3
H-bond donors ≤ 5
✓ 4
H-bond acceptors ≤ 10
Passes all rules — good oral bioavailability predicted
GHS Hazard Classification
Warning
Hazards
H302Harmful if swallowedH315Causes skin irritationH319Causes serious eye irritationH335May cause respiratory irritation
Source: PubChem GHS Classification. Always consult the SDS for handling.
Chemical IdentifiersSMILES · InChI
InChI
InChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m0/s1
Constituent Elements
Isomers8 compounds with formula C₃H₇NO₂S
(2R)-2-azaniumyl-3-sulfanylpropanoate
CID 6419722 · 121.2 g/mol
2-amino-3-sulfanylpropanoic acid
CID 594 · 121.2 g/mol
(2S)-2-amino-3-sulfanylpropanoic acid
CID 92851 · 121.2 g/mol
(2S)-2-azaniumyl-3-sulfanylpropanoate
CID 6419721 · 121.2 g/mol
1,2-thiazolidine 1,1-dioxide
CID 642157 · 121.2 g/mol
2-azaniumyl-3-sulfanylpropanoate
CID 5260155 · 121.2 g/mol
cyclopropanesulfonamide
CID 15765418 · 121.2 g/mol
prop-2-ene-1-sulfonamide
CID 14028213 · 121.2 g/mol