Highly unsaturated fatty acids synthesis

Tocher, D. R. Dick, J. R. MacGlaughlin P, Bell J G. effect of diets enriched in Delta 6 desaturated fatty acids (18 3n-6 and 18 4n-3), on growth, fatty acid composition and highly unsaturated fatty acid synthesis in two populations of Arctic chair Sahelinus alpinus L.). Comp Biochem Phys B 2006,144, 245-253. 

Morais, S., Monroig, O., Zheng, X., Leaver, M.J., and Tocher, D.R. (2009) Highly unsaturated fatty acid synthesis in Atlantic salmon Characterization of ELOVL5- and ELOVL2-like elongases. Mar. Biotechnol, 11, 627-639. 

Figure 1 Fatty acid synthesis in mammals. Gene encoding enzymes are shown in italics and are based on current evidence for substrate specificities. (A) De novo fatty acid synthesis. (B) Synthesis of the highly unsaturated fatty acids AA, EPA, and DHA from Cl 8 2 oo3 and Cl 8 3 m3 obtained from the diet. Details are found within the text.

Also, bulky phosphite-modified rhodium catalysts are highly reactive for the hydroformylation of unsaturated fatty acid esters [23]. The catalyst was able to yield turnover numbers (TON) of 400-500 when moderate conditions with 20 bar synthesis gas pressure and 100°C were applied. These phosphites, like tris (2-ferf-butyl-methyl) phosphite, have higher activity than phosphines like triphenylphosphine. 

There may be several mechanisms for these metabolic effects. Unsaturated fatty acids have been shown to directly activate specific enzymes and to induce DNA synthesis and cytokine release from lymphocytes (Karsten et al., 1994). The induction of specific protein synthesis may produce the reduction in glutamine metabolism. The increase in the robustness of the fatty acid-grown hybridomas in agitated cultures could be explained by a high incorporation of the available fatty acids into the cellular phospholipids fraction, which is a major structural component of the outer membrane of the cell (Butler et al., 1999). 

As mentioned earlier, the lymphatic system is poorly developed in poultry. Absorbed lipids pass into the portal circulation and then are principally transported as triacylglycerols of the VLDL fraction. VLDLs are present in the serum at high concentrations and appear to be the major lipid precursor in the liver for egg yolk synthesis. Furthermore, fats high in unsaturated fatty acids are absorbed more readily than fats low in unsaturated fatty acids (51, 54). 

Free fatty acids, whose levels are generally raised by insulin or alcohol, influence the rate of VLDL synthesis and hence the concentration of triglycerides. About 16 g glycerol, which are mainly utilized in the liver, are released daily by lipolysis, and about 120 g free fatty acids are made available for generating energy in the heart and skeletal musculature (75%) as well as in the liver itself (25%o). These free fatty acids are bound in the plasma to albumin (50%) and lipoproteins (50%). Their extremely short plasma half-life of approx. 2 minutes emphasizes their high metabolic activity. Fatty acids are present in the plasma in saturated (no double bond) and unsaturated (various numbers of double bonds) forms. Essential fatty acids cannot be synthesized by the body, which means they must be obtained from food intake. The most important ones are multiple unsaturated fatty acids such as linolic acid (Cis-fatty acid, 2 double bonds), linolenic acid (Ci8-fatty acid, 3 double bonds), and arachidonic acid (C2o-fatty acid, 4 double bonds). Their prime function is to act as precursors for the synthesis of eicosan-oids. (s. fig. 3.10)... 

The broad applicability of the oxo synthesis is reflected by the plethora of substrates which are converted to aldehydes - for instance, diolefins such as butadiene, alkynes [61] or unsaturated fatty acids [66]. Olefinic substrates containing one or more functional groups attract much attention due to the high synthetic value of the resulting aldehyde products. The following examples refer to some relevant publications [63], and in particular to the comprehensive review by Botteghi [49]. For a detailed discussion of particular structures see [4] and [8]. 

Of interest is a unique alternative biosynthetic pathway for CLA. Ogawa et al. (2001) reported that a strain of Lactobacillus acidophilus, under micro-aerobic conditions, produced 1O-hydroxy-cA-12-octadcccnoic acid and 10-hydroxy-trans-12-octadecenoic acid as intermediates in the synthesis of cis-9, trans-11 and trans-9, cis-11 18 2. The conversion was induced by presence of linoleic acid, and a high yield of CLA was reported. Hudson et al. (1998, 2000) showed that lactic acid bacteria, including Lactobacillus, Pediococcus, and Streptococcus species, are the major unsaturated fatty acid hydrating bacteria in the rumen, converting oleic acid to 10-hydroxy stearic acid and linoleic acid to 10-hydroxy-12-octadecenoic acid and 13-hydroxy-9 octadecenoic acid. Thus, potentially, CLA may be produced also in the rumen from linoleic acid by pathways other than the classic isomerase described by Kepler et al. (1966). 

A strain of Pseudomonas putida that tolerates high concentrations of toluene circumvents toxicity by altering membrane fluidity through synthesis of trans unsaturated fatty acids in place of the cis compounds (Weber et al. 1994). 

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