IUBMB Enzyme Nomenclature


Accepted name: ascorbate ferrireductase (transmembrane)

Reaction: ascorbate[side 1] + Fe(III)[side 2] = monodehydroascorbate[side 1] + Fe(II)[side 2]

Other name(s): cytochrome b561 (ambiguous)

Systematic name: Fe(III):ascorbate oxidorectuctase (electron-translocating)

Comments: A diheme cytochrome that transfers electrons across a single membrane, such as the outer membrane of the enterocyte, or the tonoplast membrane of the plant cell vacuole. Acts on hexacyanoferrate(III) and other ferric chelates.

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


1. Flatmark, T. and Terland, O. Cytochrome b561 of the bovine adrenal chromaffin granules. A high potential b-type cytochrome. Biochim. Biophys. Acta 253 (1971) 487-491. [PMID: 4332308]

2. McKie, A.T., Barrow, D., Latunde-Dada, G.O., Rolfs, A., Sager, G., Mudaly, E., Mudaly, M., Richardson, C., Barlow, D., Bomford, A., Peters, T.J., Raja, K.B., Shirali, S., Hediger, M.A., Farzaneh, F. and Simpson, R.J. An iron-regulated ferric reductase associated with the absorption of dietary iron. Science 291 (2001) 1755-1759. [PMID: 11230685]

3. Su, D. and Asard, H. Three mammalian cytochromes b561 are ascorbate-dependent ferrireductases. FEBS J. 273 (2006) 3722-3734. [PMID: 16911521]

4. Berczi, A., Su, D. and Asard, H. An Arabidopsis cytochrome b561 with trans-membrane ferrireductase capability. FEBS Lett. 581 (2007) 1505-1508. [PMID: 17376442]

5. Wyman, S., Simpson, R.J., McKie, A.T. and Sharp, P.A. Dcytb (Cybrd1) functions as both a ferric and a cupric reductase in vitro. FEBS Lett. 582 (2008) 1901-1906. [PMID: 18498772]

6. Glanfield, A., McManus, D.P., Smyth, D.J., Lovas, E.M., Loukas, A., Gobert, G.N. and Jones, M.K. A cytochrome b561 with ferric reductase activity from the parasitic blood fluke, Schistosoma japonicum. PLoS Negl. Trop. Dis. 4 (2010) e884. [PMID: 21103361]

[EC created 2011 as EC, transferred 2018 to EC]

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