IUBMB Enzyme Nomenclature


Accepted name: phosphatidylcholine 12-monooxygenase

Reaction: a 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine + 2 ferrocytochrome b5 + O2 + 2 H+ = a 1-acyl-2-[(12R)-12-hydroxyoleoyl]-sn-glycero-3-phosphocholine + 2 ferricytochrome b5 + H2O

Glossary: ricinoleic acid = (9Z,12R)-12-hydroxyoctadec-9-enoic acid

Other name(s): ricinoleic acid synthase; oleate Δ12-hydroxylase; oleate Δ12-monooxygenase

Systematic name: 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine,ferrocytochrome-b5:oxygen oxidoreductase (12-hydroxylating)

Comments: The enzyme, characterized from the plant Ricinus communis (castor bean), is involved in production of the 12-hydroxylated fatty acid ricinoleate. The enzyme, which shares sequence similarity with fatty-acyl desaturases, requires a cytochrome b5 as the electron donor.

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


1. Galliard, T. and Stumpf, P.K. Fat metabolism in higher plants. 30. Enzymatic synthesis of ricinoleic acid by a microsomal preparation from developing Ricinus communis seeds. J. Biol. Chem. 241 (1966) 5806-5812. [PMID: 4289003]

2. Moreau, R.A. and Stumpf, P.K. Recent studies of the enzymic-synthesis of ricinoleic acid by developing castor beans. Plant Physiol. 67 (1981) 672-676. [PMID: 16661734]

3. Smith, M.A., Jonsson, L., Stymne, S. and Stobart, K. Evidence for cytochrome b5 as an electron donor in ricinoleic acid biosynthesis in microsomal preparations from developing castor bean (Ricinus communis L.). Biochem. J. 287 (1992) 141-144. [PMID: 1417766]

4. Lin, J.T., McKeon, T.A., Goodrich-Tanrikulu, M. and Stafford, A.E. Characterization of oleoyl-12-hydroxylase in castor microsomes using the putative substrate, 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine. Lipids 31 (1996) 571-577. [PMID: 8784737]

5. Broun, P. and Somerville, C. Accumulation of ricinoleic, lesquerolic, and densipolic acids in seeds of transgenic Arabidopsis plants that express a fatty acyl hydroxylase cDNA from castor bean. Plant Physiol. 113 (1997) 933-942. [PMID: 9085577]

[EC created 1984 as EC, transferred 2015 to EC]

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