Palmitoleic acid synthesis

Palmitic acid, structure of, 1062 Palmitoleic acid, structure of, 1062 PAM resin, solid-phase peptide synthesis and, 1037 Para (m), 519 Paraffin, 91 Parallel synthesis, 586 Parent peak (mass spectrum), 410 Partial charge, 36 Pasteur, Louis, 297, 307... 

PALMITOLE1C ACID. [CAS 373-49-9], Also called dr-9-hexadec-anoic acid, formula CH3 (CH2)5CH CH(CHi>7COOH. This is an unsaturated fatty acid found in nearly every fat, especially in marine oils (15-20%i. At room temperature, it is a colorless liquid. Insoluble in water soluble in alcohol and ether mp 1.0°C bp 140-141°C (5 millimeters pressure). Combustible. Palmitoleic acid is used in organic synthesis, and as a standard in chromatographic analysis. See also Vegetable Oils (Edible). 

The infamous fluoroacetic acid and the equally toxic naturally occurring even-numbered co-fhiorinated fatty acids were discussed in detail earlier (7), and several reviews are available (34,44, 66). Although not counted as being natural in the earlier survey (7), 4-fluorothreonine (837) is now considered to be a bona fide natural metabolite of Streptomyces cattleya (893), the stereochemistry of which has been confirmed by synthesis (894). In addition to the five oo-fluorinated fatty acids presented earlier (7), new studies of the seed oil of Dichapetalum toxicarium have uncovered 16-fluoro-palmitoleic acid (838), 18-fluorostearic acid (839), 18-fluorolinoleic acid (840), 20-fluoroarachidic acid (841), 20-fluoroeicosenoic acid (842), 18-fluoro-9,10-epoxystearic acid (843) (895), (Z)-16-fluorohexadec-7-enoic acid (844), (Z)-18-fluoroocta-dec-9-enoic acid (845), and (Z)-20-fluoroicos-9-enoic acid (846) (896). 

Each of the enzymatic activities located in a single polypeptide chain of the mammalian fatty acid synthetase exists as a distinct protein in E. coli. The acyl-carrier protein (ACP) of E. coli has an Mr = 8,847 and contains 4-phosphopantotheine. The dehydratase has a molecular weight of 28,000 and catalyzes either trans 2-3 or cis 3-4 dehydration of the hydroxy acid intermediates in the biosynthesis of palmitic acid. When the chain length of the hydroxy fatty acid is C[ the synthesis of palmitoleic acid is achieved as follows ... 

After fatty acid synthesis, downstream enzymes can further modify palmi-tate for various cellular functions. In the endoplasmic reticulum, the 16 carbon fatty acid can be modified to fatty acids with eighteen or more carbons known as very long chain fatty acids (VLCFA), such as stearate (18 0) by a family of elongase enzymes called elongation of very long chain fatty acids (ELOVLl-6) (Jakobsson et ah, 2006). Palmitate and stearate can also be desaturated by stearoyl-CoA desaturase-1 (SCDl) at the cis-9 carbon to palmitoleate (16 1) and oleate (18 1), respectively (Sampath and Ntambi,... 

Liver has the enzyme activity to catalyse the introduction of a single double bond into saturated fatty acids. Stearyl-CoA desaturase (EC.l.14.99.5 reaction 4.3), which catalyses the synthesis of oleic and palmitoleic acids, is present on the endoplasmic reticulum and is hormonally regulated Goshi Aranda, 1979). 

Epidemiological studies have revealed a positive correlation between the proportions of palmitoleic acid, y-linolenic acid (GLA 18 3n-6), and dihomo-y-linolenic acid (DGLA 20 3n-6) in serum cholesterol esters and the incidence of glucose intolerance and non-insulin-dependent diabetes mellitus (Vessby et al., 1994). There is also a correlation between the level of palmitoleic acid in serum and the risk of developing non-insulin-dependent diabetes mellitus. This may be attributable to dietary factors but there is a strong possibility that genetically determined differences in the activities of enzymes involved in the synthesis and metabolism of fatty acids in the body may contribute to the correlation. This occurs through the effects of the enzymes on lipid composition and on insulin sensitivity (Borkman et al, 1993). 

Palmitoleic acid can be synthesized endogenously as well as acquired directly from the diet, but a clear distinction between dietary intake and internal synthesis as the source of observed tissue concentrations is not possible. The... 

FIGURE 21-12 Routes of synthesis of other fatty acids. Palmitate is the precursor of stearate and ionger-chain saturated fatty acids, as well as the monounsaturated acids palmitoleate and oleate. Mammals cannot convert oleate to linoleate or a-linolenate (shaded pink), which are therefore required in the diet as essential fatty acids. Conversion of linoleate to other polyunsaturated fatty acids and eicosanoids is outlined. Unsaturated fatty acids are symbolized by indicating the number of carbons and the number and position of the double bonds, as in Table 10-1. 

This desaturase transforms palmitic (C16 0) and stearic (Ci8 0) acids to palmitoleic (A9 C16 1) and oleic (A9 C18 i) acids, precursors of ct>7 and ct>9 fatty acids and 7- and 9-HC. Several desatl mutants have been described (Figure 4.3). The gene is expressed in both the fat body and oenocytes and plays a role both in general lipid metabolism and in hydrocarbon synthesis (Ueyama et al., 2005 Marcillac et al., 2005a Figure 4.4). A piggyBac strain inserted in... 

Several studies have examined the effects of PA supplementation on milk FA profile. Grummer (1991) demonstrated that de novo FA synthesis decreased linearly as supplementation of dietary fat increased, and that the changes in stearic acid and PA were dependent on the ratio in the added fat. Steele and Moore (1968) reported reductions in yield and concentration of short and medium-chain FAs (from butyric to myristic acids) and dramatic increases in PA with increased dietary intake of PA the concentration of PA in milk increased from 38.7% of total FA in controls to 60.7% of total FA in cows supplemented with PA. Noble et al. (1969) reported similar changes in milk FAs when diet was supplemented with PA at 10%, they foimd that short- and medium-chain FAs decreased when compared with a no-fat control, while milk PA increased from 36.4% of total FA in controls to 49.8% of total FA in PA-treated cows. Banks et al. (1976) also observed decreases in short- and medium-chain FAs in milk, with increases observed in concentrations of PA, palmitoleic, and oleic acids. Using duodenal infusions of 500 g of PA, Enjalbert et al. (2000) reported that concentrations of PA in milk increased 30% compared with controls. Mosley et al. (2007) determined the optimmn feeding level of a by-product rich in PA (86.6%) on dry matter intake, milk yield, milk components, and milk FA profile in dairy cattle. They formd that milk FA concentrations were affected by the addition of this by-product. As the intake of PA increased with the supplemented diets, milk PA concentrations increased. When 1.5 kg/d of this by-product was consumed, milk PA concentration increased by 50% compared with the... 

The biosynthesis of FA occurs predominantly in the two subcellular compartments, chloroplasts and endoplasmic reticulum (ER) plant mitochondria also contribute to FA synthesis, but only in a very minor way. De novo synthesis of palmitic, stearic and FAs with shorter chain length and also the first desaturation step of saturated FAs e.g. palmitic acid to palmitoleic or stearic acid to oleic one occur in plastids, whereas the next desaturation steps occurs in the ER. [4,6],... 

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