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: α-eleostearic acid biosynthesis
|Superclasses:||Biosynthesis → Fatty Acid and Lipid Biosynthesis → Fatty Acid Biosynthesis → Unusual Fatty Acid Biosynthesis → Conjugated Fatty Acid Biosynthesis|
Expected Taxonomic Range: Magnoliophyta
Seed oils of a few plant species are enriched in conjugated fatty acids (fatty acids containing conjugated or non-methylene-interrupted double bonds). These conjugated double bonds are introduced by divergent forms of the FAD2 desaturase that have been named "conjugases".
The conjugases modify an existing double bond to produce the two conjugated double bonds flanking the position of the original bond. This process is sometimes accompanied by the introduction of a new double bond.
The substrates for conjugases, just like those of the desaturases, are fatty acids bound to glycerolipids such as phosphatidylcholine. Because conjugated double bonds have high rates of oxidation, seed oils rich in conjugated double bonds are used commercially as drying agents in paints and varnishes.
α-Eleostearate (18:3Δ9cis,11trans,13trans) is a conjugated fatty acid that accounts for 80% (w/w) of tung oil (the seed oil of the tung tree, Vernicia fordii). It is derived from linoleate (18:2Δ9cis,12cis) by a fatty acid conjugase that converts the 12Z double bond into a conjugated 11E-13E double bond system [Cahoon99, Dyer02].
Cahoon99: Cahoon EB, Carlson TJ, Ripp KG, Schweiger BJ, Cook GA, Hall SE, Kinney AJ (1999). "Biosynthetic origin of conjugated double bonds: production of fatty acid components of high-value drying oils in transgenic soybean embryos." Proc Natl Acad Sci U S A 96(22);12935-40. PMID: 10536026
Dyer02: Dyer JM, Chapital DC, Kuan JC, Mullen RT, Turner C, McKeon TA, Pepperman AB (2002). "Molecular analysis of a bifunctional fatty acid conjugase/desaturase from tung. Implications for the evolution of plant fatty acid diversity." Plant Physiol 130(4);2027-38. PMID: 12481086
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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