Showing Metabocard for L-cysteine (BASm0001928)

Common NameL-cysteine
DescriptionCysteine (Cys), also known as L-cysteine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (-NH2) and carboxyl (-COOH) functional groups, along with a side chain (R group) specific to each amino acid. L-alanine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Cysteine is found in all organisms ranging from bacteria to plants to animals. It is classified as an aliphatic, non-polar, sulfur-containing amino acid. 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 can occasionally be considered as an essential or conditionally essential amino acid. 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 since the 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). Oxidation of cysteine can produce a disulfide bond with another thiol and 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 they 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 important in energy metabolism. As cystine, it is a structural component of many tissues and hormones. Cysteine has clinical uses ranging from treating 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 (http://www.dcnutrition.com/AminoAcids/). Cysteine has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821 ).
Structure
Molecular FormulaC3H7NO2S
Average Mass121.15800
Monoisotopic Mass121.01975
IUPAC Name(2R)-2-amino-3-sulfanylpropanoic acid
Traditional NameL-cysteine
CAS Registry Number52-90-4
SMILES[NH3+][C@@H](CS)C(=O)[O-]
InChI IdentifierInChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m0/s1
InChI KeyXUJNEKJLAYXESH-REOHCLBHSA-N
CHEBI IDCHEBI:35235
HMDB IDHMDB0000574
Pathways
NameSMPDB/PathBank
Glutathione metabolism
Glycine, serine and threonine metabolism
Cysteine Metabolism
Transcription/Translation
Taurine and Hypotaurine Metabolism
Pantothenate and CoA Biosynthesis
Methionine Metabolism
Glutamate Metabolism
Chlorothiazide Action Pathway
Polythiazide Action Pathway
Methyclothiazide Action Pathway
Bumetanide Action Pathway
Bendroflumethiazide Action Pathway
Quinethazone Action Pathway
Ethacrynic Acid Action Pathway
Hydrochlorothiazide Action Pathway
Cyclothiazide Action Pathway
Metolazone Action Pathway
Hydroflumethiazide Action Pathway
Indapamide Action Pathway
Furosemide Action Pathway
Torsemide Action Pathway
Trichlormethiazide Action Pathway
Chlorthalidone Action Pathway
Triamterene Action Pathway
Amiloride Action Pathway
Spironolactone Action Pathway
Eplerenone Action Pathway
2-Hydroxyglutric Aciduria (D And L Form)
5-Oxoprolinuria
Cystathionine Beta-Synthase Deficiency
Dihydropyrimidine Dehydrogenase Deficiency (DHPD)
Gamma-Glutamyltransferase Deficiency
Glucose Transporter Defect (SGLT2)
Hartnup Disorder
Iminoglycinuria
Lysinuric Protein Intolerance
S-Adenosylhomocysteine (SAH) Hydrolase Deficiency
Methionine Adenosyltransferase Deficiency
Glycine N-methyltransferase Deficiency
Non Ketotic Hyperglycinemia
Dimethylglycine Dehydrogenase Deficiency
4-Hydroxybutyric Aciduria/Succinic Semialdehyde Dehydrogenase Deficiency
Sarcosinemia
Glutathione Synthetase Deficiency
Hyperinsulinism-Hyperammonemia Syndrome
Methylenetetrahydrofolate Reductase Deficiency (MTHFRD)
Hypermethioninemia
Homocarnosinosis
Homocysteine Degradation
Kidney Function
Dimethylglycine Dehydrogenase Deficiency
Hyperglycinemia, non-ketotic
Beta-mercaptolactate-cysteine disulfiduria
5-oxoprolinase deficiency
Gamma-glutamyl-transpeptidase deficiency
Gamma-cystathionase deficiency (CTH)
Homocystinuria, cystathionine beta-synthase deficiency
Succinic semialdehyde dehydrogenase deficiency
Homocystinuria-megaloblastic anemia due to defect in cobalamin metabolism, cblG complementation type
Blue diaper syndrome
Lysinuric protein intolerance (LPI)
3-Phosphoglycerate dehydrogenase deficiency
Cystinosis, ocular nonnephropathic
Cystinuria
StateSolid
Water Solubility2.31e+01 g/l
logP-2.57
logS-0.72
pKa (Strongest Acidic)2.35
pKa (Strongest Basic)9.05
Hydrogen Acceptor Count3
Hydrogen Donor Count3
Polar Surface Area63.32 Ų
Rotatable Bond Count2
Physiological Charge0
Formal Charge0
Refractivity28.22 m³·mol⁻¹
Polarizability11.46

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