A summary of the most common chemical descriptors (InChI Key and SMILES codes) for Cysteine are summarized together with 3D and 2D structures and relevant physico-chemical properties.

What is the Cysteine?

The molecule Cysteine presents a molecular formula of C3H7NO2S and its IUPAC name is (2R)-2-amino-3-sulfanylpropanoic acid.

Cysteine is an amino acid that is essential for human health. It is a sulfur-containing amino acid that is involved in a number of important biological processes in the body, including the synthesis of proteins and the production of enzymes..

Cysteine is classified as a non-essential amino acid, which means that it can be produced by the body from other amino acids. However, it is also found in a number of dietary sources, such as poultry, eggs, yogurt, and nuts..

One of the main functions of cysteine is to act as a building block for proteins. It is used to synthesize proteins that are involved in a number of important processes in the body, including the formation of collagen, a protein that belongs in the skin, connective tissue, and bones..

In addition to its role in protein synthesis, cysteine is also involved in the production of enzymes. Enzymes are proteins that catalyze chemical reactions in the body, and cysteine is a key component of many enzymes..

Cysteine has a number of potential health benefits. It has been shown to have antioxidant properties and may help to reduce oxidative stress in the body. It may also be helpful in reducing inflammation and supporting immune function..

While research on the potential health benefits of cysteine is ongoing, it is generally considered safe for most people to consume in moderate amounts. However, it is important to note that high doses of cysteine supplements may cause side effects, such as nausea, diarrhea, and stomach pain. It is always best to speak with a healthcare professional before adding any new supplement to your routine..


From all the above, this molecule is an amino acid that is essential for human health. It is involved in the synthesis of proteins and the production of enzymes, and has a number of potential health benefits. While more research is needed to fully understand its potential, cysteine is generally considered safe for most people to consume in moderation..

3D structure

Cartesian coordinates

Geometry of Cysteine in x, y and z coordinates (Å units) to copy/paste elsewhere. Generated with Open Babel software.

2D drawing


Cysteine XUJNEKJLAYXESH-REOHCLBHSA-N chemical compound 2D structure molecule svg


Molecule descriptors

IUPAC name(2R)-2-amino-3-sulfanylpropanoic acid
InChI codeInChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m0/s1

Other names (synonyms)

IUPAC nomenclature provides a standardized method for naming chemical compounds. Although this system is widely used in chemistry, many chemical compounds have also other names commonly used in different contexts. These synonyms can come from a variety of sources and are used for a variety of purposes.

One common source of synonyms for chemical compounds is the common or trivial names, assigned on the basis of appearance, properties, or origin of the molecule.

Another source of synonyms are historical or obsolete names employed in the past, however replaced nowadays by more modern or standardized names.

In addition to common and historical names, chemical compounds may also have synonyms that are specific to a particular field or industry.

  • (+)-2-Amino-3-mercaptopropionic acid
  • (2R)-2-amino-3-mercaptopropanoate
  • (2R)-2-amino-3-mercaptopropanoic acid
  • (2R)-2-amino-3-sulfanyl-propanoic acid
  • (2R)-2-amino-3-sulfanylpropanoate
  • (2R)-2-amino-3-sulfanylpropanoic acid
  • (2R)-2-amino-3-sulfanylpropanoic acid hydrochloride
  • (R)-(+)-Cysteine
  • (R)-2-Amino-3-mercaptopropanoate
  • (R)-2-Amino-3-mercaptopropanoic acid
  • (R)-2-Amino-3-mercaptopropanoicacid
  • (R)-2-Amino-3-mercaptopropionic acid
  • (R)-2-amino-3-mercapto-Propanoate
  • (R)-2-amino-3-mercapto-Propanoic acid
  • (R)-Cysteine
  • (R)?-?2-?Amino-?3-?mercaptopropionic acid
  • .alpha.-Amino-.beta.-thiolpropionic acid
  • .beta.-Mercaptoalanine
  • 064C306
  • 1ssq
  • 1xt8
  • 2-Amino-3-mercaptopropanoic acid, (R)-
  • 2-Amino-3-mercaptopropionate
  • 2-Amino-3-mercaptopropionic acid
  • 2-amino-3-mercapto-, (R)-
  • 2-amino-3-mercaptopropanoate
  • 202114-66-7
  • 3-mercapto-L-Alanine
  • 4371-52-2
  • 52-90-4
  • AI3-26559
  • AIDS002953
  • AM81648
  • BBAE7AE6-FC21-4D37-808D-C7F7A2BA637F
  • BDBM50109609
  • C-9615
  • C00097
  • CCG-266077
  • CCRIS 912
  • CS-W009027
  • Cisteinum
  • Cys
  • Cystein
  • Cysteine
  • Cysteine HCl
  • Cysteine, L-
  • Cysteinum
  • D00026
  • DB00151
  • E 920
  • E-920
  • E920
  • EC 200-158-2
  • Epitope ID:140791
  • F0001-2369
  • F8880-8973
  • FEMA No. 3263
  • GTPL4782
  • H-Cys-OH
  • HSDB 2109
  • HY-Y0337
  • Half cystine
  • Half-cystine
  • K848JZ4886
  • L Cysteine
  • L-(+)-Cysteine
  • L-2-Amino-3-mercaptopropanoate
  • L-2-Amino-3-mercaptopropanoic acid
  • L-2-Amino-3-mercaptopropionic acid
  • L-Alanine, 3-mercapto-
  • L-Cys
  • L-Cystein
  • L-Cysteine (JP17)
  • L-Cysteine from non-animal source
  • L-Cysteine-[1-13C]
  • L-Zystein
  • L-cysteine
  • M03086
  • MFCD00064306
  • NCGC00248803-01
  • NSC-8746
  • Polycysteine
  • Propanoic acid, 2-amino-3-mercapto-, (R)-
  • Propanoic acid, 2-amino-3-mercapto-, (R)-
  • Q-201286
  • Q-201328
  • Q186474
  • Q27115093
  • STR02584
  • Thioserine
  • alpha-Amino-beta-mercaptopropanoic acid, L-
  • alpha-Amino-beta-mercaptopropionic acid, L-
  • alpha-Amino-beta-thiolpropionic acid
  • alpha-Amino-beta-thiolpropionic acid, L-
  • b-Mercaptoalanine
  • beta-Mercaptoalanine
  • beta-Mercaptoalanine, L-
  • bmse000034
  • bmse000975
  • cisteina
  • cysteine
  • l-cycteine
  • racemic cysteine
  • s5635

Reference codes for other databases

There exist several different chemical codes commonly used in orded to identify molecules:
  • ZINC895042
  • UNII-K848JZ4886
  • AKOS015854128
  • DTXSID8022876
  • CHEMBL863
  • CHEBI:17561
  • EINECS 200-158-2

Physico-Chemical properties

IUPAC name(2R)-2-amino-3-sulfanylpropanoic acid
Molecular formulaC3H7NO2S
Molecular weight121.158
Melting point (ºC)
Boiling point (ºC)
Density (g/cm3)
Molar refractivity28.94
Topological polar surface area102.1

LogP and topological polar surface area (TPSA) values were estimated using Open Babel software.

The n-octanol/water partition coeficient (Kow) data is applied in toxicology and drug research. Kow values are used, to guess the environmental fate of persistent organic pollutants. High partition coefficients values, tend to accumulate in the fatty tissue of organisms. Molecules with a log(Kow) (or LogP) greater than 5 are considered to bioaccumulate.

TPSA values are the sum of the surface area over all polar atoms or molecules, mainly oxygen and nitrogen, also including hydrogen atoms.

In medicinal chemistry, TPSA is used to assess the ability of a drug to permeabilise cells.

For molecules to penetrate the blood-brain barrier (and act on receptors in the central nervous system), TPSA values below 90 Å2 are required. Thus, molecules with a polar surface area greater than 140 Å2 tend to be poorly permeable to cell membranes.