Very Long Fatty Acids

S Biosynthesis of Wax Components 6.4.2JJ Very Long Fatty Acids 

Wax ester biosynthesis probably involves an acyl transfer mechanism. The high thioesterase activity found in crude plant extracts makes it difficult to demonstrate acyl-CoA involvement in wax ester synthesis. However, partial purification of an acetone powder extract from the leaves of B. oleracea gave a protein fraction that catalyzed an acyl-CoA-dependent esterification of fatty alcohols (222). Additionally the acetone powder extract from B. oleracea leaves appeared to catalyze the direct transfer of acyl moieties from phospholipids to fatty alcohols. The leaf extract also catalyzed under appropriate conditions the esterification of fatty alcohols to free fatty acids. The transacylase mechanism is likely to be the main mechanism of wax ester synthesis in vivo. The fact that labeled wax esters were synthesized by a membrane-bound microsomal fraction from Hordeum vulgare leaves following incubation with radioactive alcohols, but not after incubation with free fatty acids (17), is consistent with the proposed acyl transfer mechanism. In E. gracilis the acyl-CoA reductase is functionally coupled to the acyl transferase (227). Both of these activities were solubilized from the microsomes 

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Fig. 1.3 Various structures of lipid A in different bacteria. The most conserved part of lipid A is its backbone, disaccharide of glucosamine. The groups connecting to the backbone of lipid A could be different from one bacterium to another. (A) In E. coli lipid A there are two phosphates and six fatty acid chains connecting to the backbone. (B) In F. tularensis lipid A there are only one phosphate and four fatty acid chains. (C) In the lipid A of S. typhimurium there is an additional second fatty acid chain at 2-position. (D) In R. etli lipid A there is a very long fatty acid chain at...

LpxXL IpxXL Add a very long fatty acid chain to the fS2 -position of lipid A (Haag et al., 2009). 

The OH functional acrylics in the GI metal finishing area are used mostly as one coat finishes for products intended for interior use or for products with a limited life expectancy. The coatings achieved are hard, glossy, scuff resistant but with a tendency to detach from the substrate after a blow etc. This is because acrylics do not easily wet a substrate like an alkyd, which has very low surface energy because of its long fatty acid chains. This section of the GI finishing market often cuts comers on pretreatment of metals, making the acrylic more difficult to formulate with effective adhesion. 

More frequentiy, alkyd resias are described by a combiaed classification ia terms of thek oil length, the type of fatty acids, and any unusual kigredients. Such descriptions as an isophthaUc, very long tall oil alkyd a medium oil dehydrated castor-PE ( pentaerythritol, not polyethylene) alkyd or a short oil lauric-ben2oic alkyd, immediately project the general properties of the reski. 

The major components of camauba wax are aHphatic and aromatic esters of long-chain alcohols and acids, with smaller amounts of free fatty acids and alcohols, and resins. Camauba wax is very hard, with a penetration of 2 dmm at 25°C and only 3 dmm at 43.3°C. Camauba also has one of the higher melting points for the natural waxes at 84°C, with a viscosity of 3960 rare]/s at 98.9°C, an acid number of 8, and a saponification number of 80. 

The mechanism of inhibition by the salts of the long chain fatty acids has been examined . It was concluded that, in the case of the lead salts, metallic lead was first deposited at certain points and that at these points oxygen reduction proceeded more easily, consequently the current density was kept sufficiently high to maintain ferric film formation in addition, any hydrogen peroxide present may assist in keeping the iron ions in the oxide film in the ferric condition, consequently the air-formed film is thickened until it becomes impervious to iron ions. The zinc, calcium and sodium salts are not as efficient inhibitors as the lead salts and recent work has indicated that inhibition is due to the formation of ferric azelate, which repairs weak spots in the air-formed film. This conclusion has been confirmed by the use of C labelled azelaic acid, which was found to be distributed over the surface of the mild steel in a very heterogeneous manner. ... 

Fatty acid transport protein paralogues 1-6 FATP 1-6 Gene symbols SLC27A1-6 Solute carrier family 27A Very long-chain acyl-CoA synthetase VLCS... 

Fatty acid transport proteins (FATPs) are an evolutionary conserved family of integral membrane proteins found at the plasma membrane and on internal membranes. FATPs facilitate the unidirectional uptake and/ or intracellular activation of unesterified long-chain and very long-chain fatty acids (LCFAs) into a variety of lipid-metabolizing cells and tissues. 

In vitro and ex vivo studies have shown that FATPs transport LCFAs and very long-chain fatty acids (VLCFAs) but no medium-chain fatty acids, fatty acid esters, or lipid-soluble vitamins [4]. LCFA transport is inhibited by prior protease treatment. Synthetic substrates for FATPs include 14C-labeled fatty acids and the fluorescently labeled fatty acid analogue C1 -BODEP Y-Cl 2. Using the latter substrate, differences in fatty acid uptake kinetics between FATP expressing 3T3 LI adipocytes and 3T3 LI fibroblasts, which are devoid of FATPs, can be readily appreciated (Fig. 2). 

Long-chain fatty acids (LCFAs) are aliphatic compounds with a terminal carboxyl group and with a chain length greater than 12 carbon atoms (e.g., lauric acid). Very long-chain fatty acids are fatty acids with more than 18 carbon atoms (e.g., stearic acid). 

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