Oleate desaturase

The origin of ricinoleic acid, an abundant constitu-tuent of castor beans, is also shown in Fig. 21-2. It is formed by an oleate hydroxylase that has an amino acid sequence similar to those of oleate desaturases.113 Both hydroxylation and desaturation are reactions catalyzed by diiron centers.114 Other fatty acid hydroxylases act on the alpha115 and the omega positions. The latter are members of the cytochrome P450 family.116 117... 

Figure 4 Variations on an oxidative theme the dehydrogenation/oxygenation connection. C-12-initiated oxidation catalyzed by oleate desaturase and its homolog oleate 12-hydroxylase (a) and acetylenase and its homolog epoxidase (b).

Dimorphecolic acid is one of the major fatty acids in Dimorphotheca sinuata seeds. Two complementary DNAs (cDNAs) for divergent FAD2 enzymes were isolated from developing seeds by EST sequencing and homology searches. One codes for an oleate desaturase, which introduces a trans double bond at the A-12 position of oleic acid, while the second encodes an enzyme that can convert the... 

Iwabuchi M, Kohno-Murase J, Imamura J. (2003) Delta 12-oleate desaturase-related enzymes associated with formation of conjugated trans-delta 11, cis-delta 13 double bonds. J Biol Chem 278 4603 610. 

Calendula, also known as Pot Marigold, has historically been grown as an ornamental and medicinal plant. Its seed oil contains up to 60% calendic acid an (8t,lot, 12c-18 3) co-6 trienoic acid synthesized in the plant from linoleate by a A12-oleate desaturase ... 

In sharp contrast to these experiments, Hawke et al. (1980) have clearly shown that both etiolated and greened maize leaf tissue rapidly convert oleic acid to linoleic acid and thence linolenate. Thus, the kinetics of the appearance and disappearance of oleate desaturase and linoleate desaturase differ markedly in different tissues, namely, cucumber cotyledonous tissue and maize leaf tissue. It becomes of obvious importance therefore that, in future research, the type of tissue, the history of the tissue, and the regime of conditions impinging on these tissues be taken into consideration before broad generalities can be stated. 

Garces, R. and Mancha, M. 1991. In vitro oleate desaturase in developing sunflower seeds. Phytochemistry 30 2127-2130. 

Garces, R., Sarmiento, C. and Mancha, M. 1992. Temperature regulation of oleate desaturase in sunflower seeds. Planta 186 461-465. 

Oleate desaturase expression by antisense RNA in soybean led to an oil containing over 80 % oleic acid as compared to a normal 23 %, with significant decrease in polyunsaturated fatty acids [155]. Ganoladoes not normally accumulate capric and caprylic acids. But the introduction of the Cuphea hookeriana acyl-AGP thioesterase cDNA in canola resulted in the accumulation of these two medium-chain fatty acids in the seeds [156]. In plants, 0)-6 desaturase-catalyzed pathway in the microsomes is a major source of polyunsaturated lipids, introduction of the... 

Covello, P.S. and Reed, D.W. (1996) Functional expression of the extraplastidial Arabidopsis thaliana oleate desaturase gene (FAD2) in Saccharomyces cerivisiae. Plant Physiol. Ill, 223-226. van de Loo, F.N., Broun, P., Turner, S., Somerville, C.R. (1995) An oleate 12- hydroxylase from castor (Ricinus communis L) is a fatty acyl desaturase homologue, Proc. Natl Acad. Sci. USA 92, 6743-6747. 

Serghini-Caid, H., Demandre, C., Justin, A-M. and Mazliak, P. (1988) Oleoyl-phosphatidylcholine molecular species desaturated in pea leaf microsomes - possible substrates of oleate-desaturase in other green leaves. Plant Sci. 54, 93-101. 

Most evidence suggests that oleoyl phosphatidylcholine is the true substrate of the complex oleate-desaturase system present in the endoplasmic reticulum of higher plants [ 3-6]. 

It clearly appears that in each tissue analyzed several PC molecular species can be utilized as substrates by the microsomal oleate-desaturase system. The main species are the same in all tissues but the quantitative... 

The lipids of normal and a high oleic acid mutant (1) sunflower seeds have been biochemically characterized. "In vivo" and "in vitro" incubations with [l- c3 oleate showed a lack of oleate desaturase activity in developing mutant seeds. 

In vitro" incubations of microsomes with (l- c] oleoyl-CoA were in agreement with "in vivo" experiments. Microsomes from mutant seeds lacked oleate desaturase activity after 15 DAF. 

According to the current concept, plant and animal desa-turase systems include flavoprotein,Fe-containing protein and desaturase. Thus, oleate desaturase of potato microsomes is assumed to consist sequentially of NADH-ferricyanide reductase, cytochrome and desaturase 1. At present the involvement of photosynthetic electron transport components in the linoleate desaturation remains unknown. To study this problem the effect of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), the classical inhibitor of photosynthetic electron transport, on oleate and linoleate desaturation was investigated. 

Slack, CR, Roughan, PG and Terpstra, J (1976) Some properties of a microsomal oleate desaturase from leaves. Biochem J 155 71-80... 

Plant oleate desaturase is a membrane—bound enzyme system present In the reticulum of developing seeds, aged storage tissues or growing leaves Most evidence suggests that oleoyl-phosphatldylchollne Is the true substrate of oleate-desaturase. Before subsequent desaturation oleoyl residues are Inserted Into phosphatidylcholine molecules either by an acyl-exchange mechanism between oleoyl-CoA and phospholipids or by acylation to lysophosphatldylchollne HPLC allowed us to follow the time-course of oleate acylation and desaturation In the various molecular species of phosphatidylcholine from potato mlcrosomes. ... 

These data show clearly chat six molecular species of PC containing oleoyl residues either In position 2 or In position 1 of s.n glycerol can be utilized as substrates by potato oleate-desaturase In presence of NADH, the molecular species of PC containing llnoleoyl residues are formed by direct desaturation of the previous six molecular species. The main molecular species formed after desaturation are the following l,palmltoyl-2,J C llnoleoyl PC (38.8 Z), 1,llnoleoyl-2 C llnoleoyl PC (36.8 %) and 1, C llnoleoy 1-2,llnoleoyl PC (12.3 Z). 

Working on pea leaf oleate desaturase, Murphy et al. pointed to 1,palmltoyl(stearoyl)-2,oleoyl-PC as the main substrate for oleate desaturase. In good agreement with these authors, we have found that 16 0/18 1 PC, In potato tuber, did represent 55 % of all molecular species used as substrates. 

Kang, J., Snapp, A.R., Lu, C., 2011. Identification of three genes encoding microsomal oleate desaturases (FAD2) from the oilseed crop Camelina sativa. Plant Physiol. Biochem. 49,... 

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