Chemistry:Cysteine sulfinic acid

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Cysteine sulfinic acid
Skeletal formula
Ball-and-stick model
IUPAC name
2-amino-3-sulfinopropanoic acid
3D model (JSmol)
MeSH cysteine+sulfinic+acid
Molar mass 153.15698
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Cysteine sulfinic acid, also known as 3-sulfino-L-alanine, [1] is an amino acid containing a sulfinic acid functional group. It is a white solid that is soluble in water. It is an intermediate in cysteine metabolism. It is not a coded amino acid, but is produced post-translationally.

Cysteine sulfinic acid is derived from cysteine. Cysteine is formed from cystathionine via the cystathionine gamma-lyase enzyme, and is either broken down by cysteine lyase or cystathionine gamma-lyase or enters the cysteine sulfinic acid pathway where it is oxidized by cysteine dioxygenase to form cysteine sulfinic acid. Cysteine sulfinic acid, in turn, is decarboxylated by sulfinoalanine decarboxylase to form hypotaurine, which in turn is oxidized by hypotaurine dehydrogenase to yield taurine.[2] Proteins containing this residue are found at the active site of some nitrile hydratases.[3]

Cysteine sulfinic acid (2) is an intermediate in the conversion of cysteine (1) to taurine (4).


  2. Sumizu K (1962). "Oxidation of hypotaurine in rat liver". Biochim. Biophys. Acta 63: 210–212. doi:10.1016/0006-3002(62)90357-8. PMID 13979247. 
  3. Isao Endo, Masaki Nojiri, b, Masanari Tsujimura, Masayoshi Nakasako, Shigehiro Nagashima, Masafumi Yohda, Masafumi Odaka "Focused Review: Fe-type nitrile hydratase"Journal of Inorganic Biochemistry 2001, Volume 83, Issue 4, February 2001, Pages 247–253. doi:10.1016/S0162-0134(00)00171-9