Ovothiol A

Ovothiol A (N1-methyl-4-mercaptohistidine) is a highly reducing antioxidant mercaptohistidine, which accumulates to very high levels in the eggs of certain marine invertebrates, including sea urchins, scallops and starfish,^[1] where it acts to scavenge hydrogen peroxide released during fertilization.^[2]

Ovothiol A

Names
Systematic IUPAC name (2S)-2-Amino-3-(1-methyl-4-sulfanyl-1H-imidazol-5-yl)propanoic acid
Other names 1-N-Methyl-4-mercaptohistidine
Identifiers
CAS Number	108418-13-9 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:83318 Y
ChemSpider	115159
MeSH	C061475
PubChem CID	130131
UNII	BJK39KC2PD Y
CompTox Dashboard (EPA)	DTXSID90910720
InChI InChI=1S/C7H11N3O2S/c1-10-3-9-6(13)5(10)2-4(8)7(11)12/h3-4,13H,2,8H2,1H3,(H,11,12)/t4-/m0/s1 Key: XWKKYVJREGXHFO-BYPYZUCNSA-N InChI=1/C7H11N3O2S/c1-10-3-9-6(13)5(10)2-4(8)7(11)12/h3-4,13H,2,8H2,1H3,(H,11,12)/t4-/m0/s1 Key: XWKKYVJREGXHFO-BYPYZUCNBB
SMILES CN1C=NC(=C1C[C@@H](C(=O)O)N)S
Properties
Chemical formula	C7H11N3O2S
Molar mass	201.24 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

This thiol is also found in some human pathogens including trypanosomes and members of the genus Leishmania.^[3]

It is synthesized by the addition and oxidation of cysteine to histidine by 5-histidylcysteine sulfoxide synthase, followed by methylation and further reduction.

See also

• Ergothioneine