Fatty acids, long-chain palmitoleic acid

Fig. 5 Chromatograms of the 2-nitrophenylhydrazides of a mixture of saturated and unsaturated long-chain fatty acids obtained with UV detection. Flow rate 1.2 ml/min. Eluent and column temperatures (a) methanol/water (86 14 v/v) and 50°C (b) acetonitrile/water (85 15 v/v) and 30°C. Peaks 1. capric 2. Laurie 3. myristoleic 4. eicosapentenoic 5. linolenic 6. myristic 7. docosahexenoic 8. palmitoleic 9. arachidonic 10. linoleic 11. eicosatrienoic 12. palmitic 13. oleic 14. margaric (internal standard) 15. stearic acid hydrazide. Each peak corresponds to 150 pmol.

Fats are triesters formed from a triol (glycerol) and fatty acids, which are carboxylic acids with long, unbranched alkyl chains. These alkyl chains may be saturated, or they may have one or more double bonds. Usually, the three carboxylic acids of a fat molecule are not the same. The following equation illustrates the hydrolysis of a representative fat molecule to glycerol and the conjugate bases of stearic acid, palmitoleic acid, and linoleic acid. Addition of NaCl causes the fatty acid salts to precipitate. The resulting solid is formed into bars of soap. 

In addition to even-numbered, long-chain fatty acids, the brain also contains odd-numbered fatty acids, which may contain one or more unsaturated bonds. The co isomers are related to palmitoleate and are therefore assumed to be derived from palmitoleate by elongation and a-oxidation. The precursors of the and co isomers are unknown. 

Kaneda, H. Kano, Y. Kamimura, M. Osawa, T. Kawakishi, S. Analysis of long-chain fatty acids in beer by HPLC-fluorescence detection method, JAgric.Food Chem., 1990, 38, 1363-1367. [column temp 40 derivatization gradient LOD 0.2 ng/mL LOQ 0.4 ng/mL lauric acid linolenic acid myristic acid palmitoleic acid linoleic acid palmitic acid oleic acid heptadecanoic acid stearic acid]... 

Miwa, H. Yamamoto, M. Nishida, T. Nunoi, K. Kikuchi, M. High-performance liquid chromatographic analysis of serum long-chain fatty acids by direct derivatization method, J.Chromatogr., 1987, 416, 237-245. [LOD 100-200 fmol column temp 30 capric acid lauric acid myristoleic acid eicosapentaenoic acid linolenic acid myristic acid docosahexaenoic acid palmitoleic acid arachidonic acid linoleic acid dihomolinolenic acid palmitic acid oleic acid margaric acid is internal standard stearic acid]... 

Certain long-chain unsaturated fatty acids of metabolic significance in mammals are shown in Figure 23-1. Other C20, C22, and C24 polyenoic fatty acids may be derived from oleic, linoleic, and a-flnolenic acids by chain elongation. Palmitoleic and oleic acids are not essential in the diet because the tissues can introduce a double bond at the position of a saturated fatty acid. 

As a result of impaired activity of acetyl CoA and propionyl CoA carboxylases, there are changes in the fatty acid composition of lipids in the lymphocytes of biotin-deficient rats. There is an increase in the proportion of long-chain fatty acids (C22 0 to C30 0) and odd-carbon fatty acids (Cl 5 0 to C29 0), with a decrease in the proportion of unsaturated fatty acids and the ratio of ds-vaccenic acid (C18 l )9) palmitoleic acid (C16 lft)6), which is indicative of impaired elongation and desaturation of fatty acids (Liu et al., 1994). 

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,... 

There are many unsaturated fatty acids, characterized by having an alk-ene unit or diene or polyene units in the long carbon chain rather than the alkane chain found in 92-95. Common unsaturated fatty acids are palmitoleic acid (96 C16), oleic acid (97 C18), linolenic acid (98 C18), a-linolenic acid (99 C18), and y-linolenic acid (100 C18). Other examples include arachidonic acid (101 C20), erucic acid (102 C22— found in mustard seed), and nervonic acid (103 C24— important for the biosynthesis of nerve cell myelin). 

Upon expression the seeds yield about 50% (by weight) of a liquid wax composed of high molecular weight C20 and C22 esters of straight long-chain, monounsaturated fatty acids and alcohols (up to 85% of the oil), including monoethylenic acids composed mainly of eicosenoic acid (34%) and docose-noic acid (14%) alcohols, including eicose-nol (22%) and docosenol (21%) trace amounts of oleic and palmitoleic acids. 

Once fatty acid synthetase has produced long-chain saturated fatty acids, these products can be desaturated or elongated. For desaturation, three desaturase complexes are principally involved. These insert double bonds in the A9, A12, and A15 positions, respectively. The A9-desaturase operates with acyl-ACP substrates and, like fatty acid synthetase, is present in plastids. The only A9-desaturase which has been purified to any degree is that from developing safflower seeds. The enzyme is active with 16- and 18-carbon substrates, forming palmitoleate and oleate, respectively. The source of electrons for this mixed-function oxidase appears to be reduced ferredoxin from the photosynthetic electron transport chain. ... 

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