IUBMB Enzyme Nomenclature


Accepted name: L-cysteinyl-L-histidinylsulfoxide synthase

Reaction: L-histidine + L-cysteine + O2 = S-(L-histidin-5-yl)-L-cysteine S-oxide + H2O

For diagram of reaction click here.

Glossary: S-(L-histidin-5-yl)-L-cysteine S-oxide = 5-{[(2R)-2-amino-2-carboxyethyl]sulfinyl}-L-histidine

Other name(s): OvoA

Systematic name: L-histidine,L-cysteine:oxygen [S-(L-histidin-5-yl)-L-cysteine S-oxide-forming]

Comments: Requires Fe2+ for activity. The enzyme participates in ovothiol biosynthesis. It also has some activity as EC, cysteine dioxygenase, and can perform the reaction of EC, γ-glutamyl hercynylcysteine sulfoxide synthase, albeit with low activity [4].

Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:


1. Braunshausen, A. and Seebeck, F.P. Identification and characterization of the first ovothiol biosynthetic enzyme. J. Am. Chem. Soc. 133 (2011) 1757-1759. [PMID: 21247153]

2. Song, H., Leninger, M., Lee, N. and Liu, P. Regioselectivity of the oxidative C-S bond formation in ergothioneine and ovothiol biosyntheses. Org. Lett. 15 (2013) 4854-4857. [PMID: 24016264]

3. Mashabela, G.T. and Seebeck, F.P. Substrate specificity of an oxygen dependent sulfoxide synthase in ovothiol biosynthesis. Chem. Commun. (Camb.) 49 (2013) 7714-7716. [PMID: 23877651]

4. Song, H., Her, A.S., Raso, F., Zhen, Z., Huo, Y. and Liu, P. Cysteine oxidation reactions catalyzed by a mononuclear non-heme iron enzyme (OvoA) in ovothiol biosynthesis. Org. Lett. 16 (2014) 2122-2125. [PMID: 24684381]

[EC created 2015]

Return to EC 1.14.99 home page
Return to EC 1.14 home page
Return to EC 1 home page
Return to Enzymes home page
Return to IUBMB Biochemical Nomenclature home page