ContaminantDB: L-Cysteine

Identification Taxonomy Biological Properties Physical Properties Toxicity Profile Spectra Concentrations Links References Targets (20)XML

Record Information

Version

1.0

Creation Date

2014-08-29 05:47:31 UTC

Update Date

2026-03-31 17:06:53 UTC

Accession Number

CHEM003116

Identification

Common Name

L-Cysteine

Class

Small Molecule

Description

Cysteine is a uremic toxin. Uremic toxins can be subdivided into three major groups based upon their chemical and physical characteristics: 1) small, water-soluble, non-protein-bound compounds, such as urea; 2) small, lipid-soluble and/or protein-bound compounds, such as the phenols and 3) larger so-called middle-molecules, such as beta2-microglobulin. Chronic exposure of uremic toxins can lead to a number of conditions including renal damage, chronic kidney disease and cardiovascular disease. Cysteine is a naturally occurring, sulfur-containing amino acid that is found in most proteins, although only in small quantities. Cysteine is unique amongst the twenty natural amino acids as it contains a thiol group. Thiol groups can undergo oxidation/reduction (redox) reactions; when cysteine is oxidized it can form cystine, which is two cysteine residues joined by a disulfide bond. This reaction is reversible: as reduction of this disulphide bond regenerates two cysteine molecules. The disulphide bonds of cystine are crucial to defining the structures of many proteins. Cysteine is often involved in electron-transfer reactions, and help the enzyme catalyze its reaction. Cysteine is also part of the antioxidant glutathione. N-acetyl-L-cysteine (NAC) is a form of cysteine where an acetyl group is attached to cysteine's nitrogen atom and is sold as a dietary supplement. Cysteine is named after cystine, which comes from the Greek word kustis meaning bladder - cystine was first isolated from kidney stones. As cysteine contains a sulphydryl group, it can undergo redox reactions. Oxidation of cysteine can produce a disulfide bond with another thiol, or further oxidation can produce sulphfinic or sulfonic acids. The cysteine thiol group is also a nucleophile and can undergo addition and substitution reactions. Thiol groups become much more reactive when they are ionized, and cysteine residues in proteins have pKa values close to neutrality, so are often in their reactive thiolate form in the cell. The thiol group also has a high affinity for heavy metals and proteins containing cysteine will bind metals such as mercury, lead and cadmium tightly. Due to this ability to undergo redox reactions, cysteine has antioxidant properties. Cysteine is an important source of sulfur in human metabolism, and although it is classified as a non-essential amino acid, cysteine may be essential for infants, the elderly, and individuals with certain metabolic disease or who suffer from malabsorption syndromes. Cysteine may at some point be recognized as an essential or conditionally essential amino acid. Cysteine is important in energy metabolism. As cystine, it is a structural component of many tissues and hormones. Cysteine has clinical uses ranging from baldness to psoriasis to preventing smoker's hack. In some cases, oral cysteine therapy has proved excellent for treatment of asthmatics, enabling them to stop theophylline and other medications. Cysteine also enhances the effect of topically applied silver, tin and zinc salts in preventing dental cavities. In the future, cysteine may play a role in the treatment of cobalt toxicity, diabetes, psychosis, cancer and seizures.

Contaminant Sources

Cosmetic Chemicals
EAFUS Chemicals
FooDB Chemicals
HMDB Contaminants - Feces
HMDB Contaminants - Urine
HPV EPA Chemicals
STOFF IDENT Compounds
T3DB toxins

Contaminant Type

Amine
Dietary Supplement
Drug
Food Toxin
Household Toxin
Metabolite
Natural Compound
Nutraceutical
Nutritional Support
Organic Compound
Supplement
Uremic Toxin

Chemical Structure

MOL SDF PDB SMILES InChI

Synonyms

Value	Source
(2R)-2-Amino-3-mercaptopropanoic acid	ChEBI
(2R)-2-Amino-3-sulfanylpropanoic acid	ChEBI
(R)-2-Amino-3-mercaptopropanoic acid	ChEBI
C	ChEBI
Cys	ChEBI
CYSTEINE	ChEBI
e 920	ChEBI
e-920	ChEBI
e920	ChEBI
FREE cysteine	ChEBI
L-2-Amino-3-mercaptopropionic acid	ChEBI
L-Cystein	ChEBI
L-Zystein	ChEBI
Ecolan	Kegg
(2R)-2-Amino-3-mercaptopropanoate	Generator
(2R)-2-Amino-3-sulfanylpropanoate	Generator
(2R)-2-Amino-3-sulphanylpropanoate	Generator
(2R)-2-Amino-3-sulphanylpropanoic acid	Generator
(R)-2-Amino-3-mercaptopropanoate	Generator
L-2-Amino-3-mercaptopropionate	Generator
(+)-2-Amino-3-mercaptopropionic acid	HMDB
(R)-(+)-Cysteine	HMDB
(R)-2-Amino-3-mercapto-propanoate	HMDB
(R)-2-Amino-3-mercapto-propanoic acid	HMDB
(R)-Cysteine	HMDB
2-Amino-3-mercaptopropanoate	HMDB
2-Amino-3-mercaptopropanoic acid	HMDB
2-Amino-3-mercaptopropionate	HMDB
2-Amino-3-mercaptopropionic acid	HMDB
3-Mercapto-L-alanine	HMDB
Acetylcysteine	HMDB
alpha-Amino-beta-thiolpropionic acid	HMDB
b-Mercaptoalanine	HMDB
beta-Mercaptoalanine	HMDB
Carbocysteine	HMDB
Cisteina	HMDB
Cisteinum	HMDB
Cystein	HMDB
Cysteinum	HMDB
Half-cystine	HMDB
L Cysteine	HMDB
L-(+)-Cysteine	HMDB
L-2-Amino-3-mercaptopropanoate	HMDB
L-2-Amino-3-mercaptopropanoic acid	HMDB
Polycysteine	HMDB
Thioserine	HMDB
Cysteine hydrochloride	HMDB
Zinc cysteinate	HMDB
Half cystine	HMDB

Chemical Formula

C₃H₇NO₂S

Average Molecular Mass

121.158 g/mol

Monoisotopic Mass

121.020 g/mol

CAS Registry Number

52-90-4

IUPAC Name

(2R)-2-amino-3-sulfanylpropanoic acid

Traditional Name

L-cysteine

SMILES

N[C@@H](CS)C(O)=O

InChI Identifier

InChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m0/s1

InChI Key

XUJNEKJLAYXESH-REOHCLBHSA-N

Chemical Taxonomy

Description

belongs to the class of organic compounds known as cysteine and derivatives. Cysteine and derivatives are compounds containing cysteine or a derivative thereof resulting from reaction of cysteine at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom.

Kingdom

Organic compounds

Super Class

Organic acids and derivatives

Class

Carboxylic acids and derivatives

Sub Class

Amino acids, peptides, and analogues

Direct Parent

Cysteine and derivatives

Alternative Parents

Substituents

Cysteine or derivatives
Alpha-amino acid
L-alpha-amino acid
Amino acid
Alkylthiol
Carboxylic acid
Monocarboxylic acid or derivatives
Organic oxygen compound
Primary amine
Organosulfur compound
Organooxygen compound
Organonitrogen compound
Organic nitrogen compound
Primary aliphatic amine
Carbonyl group
Amine
Hydrocarbon derivative
Organopnictogen compound
Organic oxide
Aliphatic acyclic compound

Molecular Framework

Aliphatic acyclic compounds

External Descriptors

proteinogenic amino acid (CHEBI:17561 )
L-alpha-amino acid (CHEBI:17561 )
cysteine (CHEBI:17561 )
serine family amino acid (CHEBI:17561 )
Common amino acids (C00097 )

Biological Properties

Status

Detected and Not Quantified

Origin

Endogenous

Cellular Locations

Cytoplasm
Extracellular
Membrane
Mitochondria

Biofluid Locations

Not Available

Tissue Locations

Adrenal Cortex
Epidermis
Fibroblasts
Intestine
Kidney
Liver
Muscle
Myelin
Neuron
Placenta
Platelet
Prostate
Skeletal Muscle
Spleen
Testes
Thyroid Gland

Pathways

Name	SMPDB Link	KEGG Link
Cysteine Metabolism	SMP00013	map00270
Glutathione Metabolism	SMP00015	map00480
Glycine and Serine Metabolism	SMP00004	map00260
Methionine Metabolism	SMP00033	map00270
Pantothenate and CoA Biosynthesis	SMP00027	map00770
Taurine and Hypotaurine Metabolism	SMP00021	map00430
Transcription/Translation	SMP00019	Not Available
Gamma-glutamyl-transpeptidase deficiency	SMP00501	Not Available
Gamma-Glutamyltransferase Deficiency	SMP00183	Not Available
Hypermethioninemia	SMP00341	Not Available

Applications

flour treatment agent

Biological Roles

Chemical Roles

EC 4.3.1.3 (histidine ammonia-lyase) inhibitor

Physical Properties

State

Solid

Appearance

White powder.

Experimental Properties

Property	Value
Melting Point	240 dec°C
Boiling Point	Not Available
Solubility	2.77E+005 mg/L (at 25°C)

Predicted Properties

Property	Value	Source
Water Solubility	23.1 g/L	ALOGPS
logP	-2.6	ALOGPS
logP	-2.8	ChemAxon
logS	-0.72	ALOGPS
pKa (Strongest Acidic)	2.35	ChemAxon
pKa (Strongest Basic)	9.05	ChemAxon
Physiological Charge	0	ChemAxon
Hydrogen Acceptor Count	3	ChemAxon
Hydrogen Donor Count	3	ChemAxon
Polar Surface Area	63.32 Å²	ChemAxon
Rotatable Bond Count	2	ChemAxon
Refractivity	28.22 m³·mol⁻¹	ChemAxon
Polarizability	11.41 Å³	ChemAxon
Number of Rings	0	ChemAxon
Bioavailability	1	ChemAxon
Rule of Five	Yes	ChemAxon
Ghose Filter	No	ChemAxon
Veber's Rule	No	ChemAxon
MDDR-like Rule	No	ChemAxon

Spectra

Spectrum Type	Description	Splash Key	View
GC-MS	GC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (4 TMS)	splash10-00kb-0950000000-df7e91c95b610ff21c79	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (4 TMS)	splash10-00kb-0940000000-aefe34765fb447090a23	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (4 TMS)	splash10-00kb-0970000000-10a155c40ea499023052	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (Non-derivatized)	splash10-00kb-0940000000-037a3a34651c3154b3b3	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Pegasus III TOF-MS system, Leco; GC 6890, Agilent Technologies) (4 TMS)	splash10-00di-9850000000-118c43e33861a6baa8d2	Spectrum
GC-MS	GC-MS Spectrum - EI-B (Non-derivatized)	splash10-014j-0690100000-0aeb88fd507505e6b718	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Non-derivatized)	splash10-00kb-0950000000-df7e91c95b610ff21c79	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Non-derivatized)	splash10-00kb-0940000000-aefe34765fb447090a23	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Non-derivatized)	splash10-00kb-0970000000-10a155c40ea499023052	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Non-derivatized)	splash10-00kb-0940000000-037a3a34651c3154b3b3	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-QQ (Non-derivatized)	splash10-0uk9-5619100000-8cb2558373966174ced3	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Non-derivatized)	splash10-00di-9850000000-118c43e33861a6baa8d2	Spectrum
GC-MS	GC-MS Spectrum - GC-EI-TOF (Non-derivatized)	splash10-0gi0-0960000000-03b2097de6f9637d29cb	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positive	splash10-004l-9100000000-4553906a941a5e87ec97	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (1 TMS) - 70eV, Positive	splash10-004i-9200000000-cfaf705cd0452d428454	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (Non-derivatized) - 70eV, Positive	Not Available	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (TMS_1_2) - 70eV, Positive	Not Available	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (TMS_1_3) - 70eV, Positive	Not Available	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (TBDMS_1_1) - 70eV, Positive	Not Available	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (TBDMS_1_2) - 70eV, Positive	Not Available	Spectrum
Predicted GC-MS	Predicted GC-MS Spectrum - GC-MS (TBDMS_1_3) - 70eV, Positive	Not Available	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - Quattro_QQQ 10V, Positive (Annotated)	splash10-00b9-9600000000-374c5872d68662832769	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - Quattro_QQQ 25V, Positive (Annotated)	splash10-0a4i-9000000000-ddbd3df6b8dbb280ffba	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - Quattro_QQQ 40V, Positive (Annotated)	splash10-0a4i-9000000000-320a2c77443b80ebf733	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-0089-0900000000-9dcd3d757c5cd11eb18e	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-0udi-3900000000-212e081fe83ad70de0ad	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-000i-9000000000-2eb01f41c225f614db24	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-001i-0900000000-a19834eb7cb9f211fdf2	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-00di-0900000000-2458f2587761e779ed93	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-0a4i-9000000000-77e590f0ed26f69b31c0	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-0udi-3900000000-7b1857997392b006b95f	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT (LTQ Orbitrap XL, Thermo Scientfic) , Positive	splash10-0a4i-3900000000-bc268c27ed5706a4bbd2	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - CE-ESI-TOF (CE-system connected to 6210 Time-of-Flight MS, Agilent) , Positive	splash10-00di-0900000000-4573390bccc238e3c91b	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT , positive	splash10-0udi-3900000000-212e081fe83ad70de0ad	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - LC-ESI-ITFT , positive	splash10-0udi-3900000000-7b1857997392b006b95f	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - QqQ 14V, negative	splash10-001i-9000000000-5dc69d3b59bd15290aef	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 10V, Positive	splash10-0a6r-9100000000-ed3c9c47ed98679090ab	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 0V, Positive	splash10-00di-2900000000-8bb219d17ccdf7ac0a5d	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 30V, Positive	splash10-0a4i-9000000000-e623d5a27b5075c82b4d	Spectrum
LC-MS/MS	LC-MS/MS Spectrum - 10V, Positive	splash10-056r-9100000000-4e26cc13af7c878115f7	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Positive	splash10-00b9-9600000000-4352a7b437c34c04d9f0	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Positive	splash10-004i-9200000000-7b4cd034c717561c61dd	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Positive	splash10-052f-9000000000-8f351cbca6ffed356a9b	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 10V, Negative	splash10-00di-6900000000-51ba0df80cc33423420b	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 20V, Negative	splash10-0079-9400000000-4aa2b707c391d5838d29	Spectrum
Predicted LC-MS/MS	Predicted LC-MS/MS Spectrum - 40V, Negative	splash10-001i-9000000000-95c7672c7836c0fc51c9	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
1D NMR	1H NMR Spectrum	Not Available	Spectrum
1D NMR	13C NMR Spectrum	Not Available	Spectrum
2D NMR	[1H,1H] 2D NMR Spectrum	Not Available	Spectrum
2D NMR	[1H,13C] 2D NMR Spectrum	Not Available	Spectrum

Toxicity Profile

Route of Exposure

Endogenous, Ingestion, Dermal (contact)

Mechanism of Toxicity

Uremic toxins such as cysteine are actively transported into the kidneys via organic ion transporters (especially OAT3). Increased levels of uremic toxins can stimulate the production of reactive oxygen species. This seems to be mediated by the direct binding or inhibition by uremic toxins of the enzyme NADPH oxidase (especially NOX4 which is abundant in the kidneys and heart) (3). Reactive oxygen species can induce several different DNA methyltransferases (DNMTs) which are involved in the silencing of a protein known as KLOTHO. KLOTHO has been identified as having important roles in anti-aging, mineral metabolism, and vitamin D metabolism. A number of studies have indicated that KLOTHO mRNA and protein levels are reduced during acute or chronic kidney diseases in response to high local levels of reactive oxygen species (4). Although classified as a non-essential amino acid cysteine may be essential for infants, the elderly, and individuals with certain metabolic disease or who suffer from malabsorption syndromes. Cysteine can usually be synthesized by the human body under normal physiological conditions if a sufficient quantity of methionine is available. Due to the ability of thiols to undergo redox reactions, cysteine has antioxidant properties. Cysteine's antioxidant properties are typically expressed in the tripeptide glutathione, which occurs in humans as well as other organisms. The systemic availability of oral glutathione (GSH) is negligible; so it must be biosynthesized from its constituent amino acids, cysteine, glycine, and glutamic acid. Glutamic acid and glycine are readily available in the diets of most industrialized countries, but the availability of cysteine can be the limiting substrate. Cysteine is also an important source of sulfide in human metabolism. The sulfide in iron-sulfur clusters and in nitrogenase is extracted from cysteine, which is converted to alanine in the process. In a 1994 report released by five top cigarette companies, cysteine is one of the 599 additives to cigarettes. Its use or purpose, however, is unknown, like most cigarette additives. Its inclusion in cigarettes could offer two benefits: Acting as an expectorant, since smoking increases mucus production in the lungs; and increasing the beneficial antioxidant glutathione (which is diminished in smokers).

Metabolism

Uremic toxins tend to accumulate in the blood either through dietary excess or through poor filtration by the kidneys. Most uremic toxins are metabolic waste products and are normally excreted in the urine or feces.

Toxicity Values

Not Available

Lethal Dose

Not Available

Carcinogenicity (IARC Classification)

No indication of carcinogenicity to humans (not listed by IARC).

Uses/Sources

For the prevention of liver damage and kidney damage associated with overdoses of acetaminophen

Minimum Risk Level

Not Available

Health Effects

Chronic exposure to uremic toxins can lead to a number of conditions including renal damage, chronic kidney disease and cardiovascular disease.

Symptoms

As a uremic toxin, this compound can cause uremic syndrome. Uremic syndrome may affect any part of the body and can cause nausea, vomiting, loss of appetite, and weight loss. It can also cause changes in mental status, such as confusion, reduced awareness, agitation, psychosis, seizures, and coma. Abnormal bleeding, such as bleeding spontaneously or profusely from a very minor injury can also occur. Heart problems, such as an irregular heartbeat, inflammation in the sac that surrounds the heart (pericarditis), and increased pressure on the heart can be seen in patients with uremic syndrome. Shortness of breath from fluid buildup in the space between the lungs and the chest wall (pleural effusion) can also be present.

Treatment

Kidney dialysis is usually needed to relieve the symptoms of uremic syndrome until normal kidney function can be restored.

Concentrations

Not Available

External Links

DrugBank ID

DB00151

HMDB ID

HMDB0000574

FooDB ID

FDB012678

Phenol Explorer ID