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MetaCyc Pathway: ricinoleate biosynthesis
Inferred from experiment

Pathway diagram: ricinoleate biosynthesis

This view shows enzymes only for those organisms listed below, in the list of taxa known to possess the pathway. If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.

Synonyms: ricinoleic acid biosynthesis

Superclasses: BiosynthesisFatty Acid and Lipid BiosynthesisFatty Acid Biosynthesis

Some taxa known to possess this pathway include : Ricinus communis

Expected Taxonomic Range: Viridiplantae

Plant oils contribute significantly to the caloric intake of humans and animals. Vegetable oils are extracted from a number of plant sources, and soybean oil accounts for nearl 68% of vegetable oil production in the US. Apart from the major use as food, plant oils have several industrial uses. Laurate from coconut oil is extensively used in the manufacture of soaps and detergents.

The kinds of fatty acid composition in different seed oils determine the quality and use of the oil. Plants contain significant amounts of 2-hydroxy fatty acids in their spingolipids. Oil from Ricinus communis (the source of castor oil) contains almost 90% ricinoleate (D-12-hydroxy-octadec-cis-9-enoate). The compound occurs throughout the plant kingdom, and the enzyme responsible for the hydroxylation (a mixed function oxygenase) shares homology with other fatty acyl desaturases [vandeLoo95]. Ricinoleate is produced in large scale for its use in a variety of compounds. Pyrolyzation of ricinoleate yields sebacic acid, which is used to produce some types of nylon and high temp greases for jet engines.

In developing castor bean, the substrate for the hydroxylase is not the free acid but rather microsomal oleoyl phosphatidylcholine. It requires electron channeling from NADPH to the hydroxylase. Electrons are transferred from NAD(P)H to the site of hydroxylation via a cytochrome b5, similarly to animal stearoyl-CoA desaturase [Smith92a].

Ricinoleate is released from the lipid membrane complex by the action of a specific phospholipase that oxygenates fatty acids.

Created 10-Feb-2010 by Pujar A, Boyce Thompson Institute
Revised 01-Oct-2014 by Caspi R, SRI International


Broun97: Broun P, Somerville C (1997). "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(3);933-42. PMID: 9085577

Smith92a: Smith MA, Jonsson L, Stymne S, Stobart K (1992). "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 ( Pt 1);141-4. PMID: 1417766

vandeLoo95: van de Loo FJ, Broun P, Turner S, Somerville C (1995). "An oleate 12-hydroxylase from Ricinus communis L. is a fatty acyl desaturase homolog." Proc Natl Acad Sci U S A 92(15);6743-7. PMID: 7624314

Other References Related to Enzymes, Genes, Subpathways, and Substrates of this Pathway

Brown12: Brown AP, Kroon JT, Swarbreck D, Febrer M, Larson TR, Graham IA, Caccamo M, Slabas AR (2012). "Tissue-specific whole transcriptome sequencing in castor, directed at understanding triacylglycerol lipid biosynthetic pathways." PLoS One 7(2);e30100. PMID: 22319559

Latendresse13: Latendresse M. (2013). "Computing Gibbs Free Energy of Compounds and Reactions in MetaCyc."

Lederer94: Lederer F (1994). "The cytochrome b5-fold: an adaptable module." Biochimie 76(7);674-92. PMID: 7893819

Lin96: Lin JT, McKeon TA, Goodrich-Tanrikulu M, Stafford AE (1996). "Characterization of oleoyl-12-hydroxylase in castor microsomes using the putative substrate, 1-acyl-2-oleoyl-sn-glycero-3-phosphocholine." Lipids 31(6);571-7. PMID: 8784737

Lu07: Lu C, Wallis JG, Browse J (2007). "An analysis of expressed sequence tags of developing castor endosperm using a full-length cDNA library." BMC Plant Biol 7;42. PMID: 17672910

Napier03: Napier JA, Michaelson LV, Sayanova O (2003). "The role of cytochrome b5 fusion desaturases in the synthesis of polyunsaturated fatty acids." Prostaglandins Leukot Essent Fatty Acids 68(2);135-43. PMID: 12538077

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
Page generated by Pathway Tools version 19.5 (software by SRI International) on Sun May 1, 2016, biocyc14.