Normal fatty acids

To prevent dissociation in water the studies of fatty acids (C 02H) are performed in a medium of strong acidity (pH = 1), arranged by addition of HCl. The results for some fatty aeids in acidic solution obtained in different studies [30-33] are illustrated in Fig. 3.8. 

It is seen from Fig. 3.9 that for lower acids (Cj-Cg) the corresponding theoretical curves are indistinguishable, i.e. hoth theoretical models provide good description of the adsorption behaviour. However, for decanoic and lauric acids the aggregation model leads to essentially smaller deviation from the experimental data (by a factor of 2 for lauric acid) then the Frumkin model. Similarly to the normal alcohol series, the increase of the Frumkin constant a with n -takes place, and for even homologues the value of a is essentially higher, cf. Fig. 3.9. 

The slope of the dependence b(nc) for fatty acids is the same as for normal alcohols, i.e. the increments of free energy per CHj group for these substances are approximately equal 

For the dodecanoic acid, in contrast to 1-dodecanol, the aggregation model yields a quite high aggregation number of n = 4, while no indications exist for the formation of larger clusters. Also, no data for spread dodecanoic acid monolayers could be found in literature which exhibit characteristic inflection points in the FI-A isotherm. The dependencies at 15-20°C usually correspond to the type of gaseous monolayers [34]. Therefore, a certain similarity exists in the behaviour of fatty acids and alcohols, i.e. for a smaller number of methylene groups the system 

---

In the endoplasmic reticulum of eukaryotic cells, the oxidation of the terminal carbon of a normal fatty acid—a process termed ch-oxidation—can lead to the synthesis of small amounts of dicarboxylic acids (Figure 24.27). Cytochrome P-450, a monooxygenase enzyme that requires NADPH as a coenzyme and uses O, as a substrate, places a hydroxyl group at the terminal carbon. Subsequent oxidation to a carboxyl group produces a dicarboxylic acid. Either end can form an ester linkage to CoA and be subjected to /3-oxidation, producing a... 

The key enzymes involved in the biosynthetic pathways of the Type I compounds are the fatty acid synthesis enzymes acetyl-CoA carboxylase and fatty acid synthetase. These enzymes are similar to those that produce the normal fatty acids used by all organisms. The resulting products are palmitic (16 car-... 

Whilst sodium bicarbonate is the primary blowing agent, it is common compounding practice to use it in conjunction with a proportion of a weak acid, such as stearic or oleic acid, whose function is to trigger the reaction and assist in the uniform decomposition of the bicarbonate. The higher than normal fatty acid level will also act as a process aid, facilitating the bubble expansion process. 

Attractive Compounds. The female-produced sex pheromone of the yellow mealworm beetle, Tenebrio molitor, is (R)-4-methyl- 1-nonanol [316] 163 (Scheme 18). Careful investigations on the biosynthesis of this compound [317] revealed that it is produced through a modification of normal fatty acid biosynthesis (Fig. 1, Fig. 2) propanoate serves as the starter, while formal chain elongation with acetate, propanoate, and acetate (accompanied by removal of the oxygens) produces 4-methylnonanoate which yields the pheromone alcohol after reduction. The structures and role of proteins that are present in the hemolymph or secreted by the tubular accessory glands of T. molitor, and that may carry lipophilic chemical messengers (like pheromones) are under investigation [318,319]. 

Fatty acids with an odd number of C atoms are treated in the same way as normal fatty acids—i. e., they are taken up by the cell with ATP-dependent activation to acyl CoA and are transported into the mitochondria with the help of the carnitine shuttle and broken down there by p-oxidation (see p. 164). In the last step, propionyl CoA arises instead of acetyl CoA. This is first carboxylated by propionyl CoA carboxylase into fSj-methylmalonyl CoA [3], which—after isomerization into the (i ) enantiomer (not shown see p. 411)—is isomerized into succinyl CoA [4]. 

By the electrolysis of the salts of the normal fatty acids. In this process nascent oxygen acts upon the fatty acid, converting its o.xatyl into carbonic anhydride, the positive radicai being sot free —... 

Catalytic hydrogenation of vegetable oils is widely used to form harder fats and to decrease the content of polyunsaturated fatty acyl groups. The products have a greatly increased resistance to rancidity. However, they also contain fats with trans double bonds as well as isomers with double bonds in unusual positions.251 253 Such compounds may interfere with normal fatty acid metabolism and also appear to affect serum lipoprotein levels adversely. Trans fatty acids are present in some foods. One hundred grams of butter contain 4-8 g, but hydrogenated fats often contain much more. It has been estimated that in the United States trans fatty acids account for 6-8% of total dietary fat.253... 

Analytical data for the other classes of organic compounds show normal fatty acids to be more than an order of magnitude greater than n-alkanes in modem sediments, typically 26 /Agrams/gram and 1.5 /Agram/ gram, respectively for ancient sediments, the abundances were found to... 

Kvenvolden, K. A., Molecular Distributions of Normal Fatty Acids and... 

Results of chemical analysis showed that the glucosamine and total fatty acid contents of the KDO depleted, toxic lipid A and the nontoxic lipid A were essentially the same but that the nontoxic lipid A was significantly lower in the phosphorus content (Table V). The molar ratio of glucosamine phosphorus fatty acids was 2 2 4 for the toxic lipid A and 2 1 4 for the nontoxic lipid A. The relative molar distribution of normal fatty acids (lauric, myristic, and palmitic acids) and the 3-hydroxymyristic acid did not indicate a correlation between the content of these components and toxicity. The nontoxic lipid A possessed as high a tumor regression activity when combined with CWS as did the purified... 

Figure 6.7 Biosynthesis of (2 ,4 ,6 )-5-ethyl-3-methyl-2,4,6-nonatriene, pheromone component of Carpophilus freemani Dobson (Nitidulidae). The pathway is a modification of normal fatty acid biosynthesis, involving initiation with acetate elongation with first propionate (to provide the methyl branch), then butyrate (to provide the ethyl branch) and chain termination with a second butyrate. The final butyrate to add suffers a loss of C02, after adding in a unique head-to-head reaction. Intermediates of the pathway likely occur as activated (e.g. CoA) derivatives (Petroski et al., 1994 Bartelt and Weisleder, 1996).

Several pheromones may be involved in mediating the mating behavior of the yellow mealworm, Tenebrio molitor L. (reviewed in Plarre and Vanderwel, 1999), but only one has been identified to date. Tanaka et al. (1986, 1989) identified the female-produced male attractantas(4/ )-(+)-4-methylnonan-l-ol(4-methylnonanol). Females produce the pheromone through a modification of normal fatty acid biosynthesis (Islam et al., 1999 Bacala, 2000). Initiation of the pathway with one unit of propionate results in the uneven number of carbons in the chain incorporation of another unit of propionate during elongation provides the methyl branch reduction of the fatty acyl intermediate produces the alcohol pheromone (Figure 6.8). 

Thus, the lipid biosynthetic enzyme system evolved in extreme halophiles to utilize the (halophilic) mevalonate pathway for synthesis of virtually all of its hydrocarbon (isoprenoid/isopranoid) chains, rather than the (non-halophilic) fatty-acid synthetase system which was retained only for synthesis of normal fatty acid chains required for incorporation into proteins of the red membrane (Pugh and Kates, unpublished data). Starting from acetate and involving lysine, which provides the branch-methyl and methine carbons [88]), the mevalonate pathway proceeds to geranylgeranyl-PP (GG-PP) [13,15,89] as follows ... 

DHA, will be able to achieve this is, at least to the present authors, far from clear. It is not beyond the bounds of possibility that such genetically modified plants may produce much less oil than the normal plant as the energy and reducing power needed (by the desaturase and elongase reactions) to produce the PUFAs must come from the same sources that are being used to synthesize the normal fatty acids. The situation in plants may parallel what was found with the production of GLA in Mucor spp. (see Section 2.2.1) You can either find strains that produce a lot of oil but have little GLA, or you can find strains that produce a lot of GLA but have little oil, but you cannot have both occurring simultaneously. It may then take additional genetic manipulations to correct this imbalance, but distortion of one metabolic pathway can only be achieved at the expense of another so this is not likely to be a trivial task. 

The lipid moiety of the glycolipids under consideration is either composed of branched-chain fatty acids (for example, mycolic acids in cord factor and in wax D) or can be a wax formed by the union of a phenolic alcohol with branched-chain fatty acids of the mycocerosic acid type, as in mycosides A and B. In the phosphoglycolipids, simple normal fatty acids have been found, accompanied by some methyl branched acids. 

Isoniazid interferes with mycolic acid synthesis by inhibiting an enoyl reductase (InhA) which forms part of the fatty acid synthase system in mycobacteria. Mycolic acids are produced by a diversion of the normal fatty acid synthetic pathway in which short-chain (16 carbon) and long-chain (24 carbon) fatty acids are produced by addition of 7 or 11 malonate extension units from malonyl coenzyme A to acetyl coenzyme A. InhA inserts a double bond into the extending fatty acid chain at the 24 carbon stage. The long-chain fatty acids are further extended and condensed to produce the 60-90 carbon (3-hydroxymycolic acids which are important components of the mycobacterial cell wall. Isoniazid is converted inside the mycobacteria to a free radical species by a catalase peroxidase enzyme, KatG. The active free radicals then attack and inhibit the enoyl reductase, InhA, by covalent attachment to the active site. 

Organic Compounds by Distribution Studies. VII. Separation and Estimation of Normal Fatty Acids. J. biol. Chem. 170, 501 (1947). 

Burlina AB, Dionisi-Vici C, Bennett MJ, Gibson KM, Servidei S, Bertini E, et al. A new syndrome with eth-ylmalonic aciduria and normal fatty acid oxidation in fibroblasts. J Pediatr 1994 124 79-86. 

Because of Its structural similarity to acetate. It is not surprising that cyclopropanecarboxyllc acid (from the mltlclde cycloprate) Is Incorporated readily Into normal fatty acid pathways. Six homologous (i>-cyclopropyl fatty acids were identified from treatment of rats, dogs, and a cow with cycloprate (7-10). Generally, these (it-cyclopropyl fatty acids were not free, but rather were esterified to produce modified hybrid lipids (vide Infra ). 

FIGURE 10.6 Aqueous solutions of sodium soaps of normal fatty acids of various chain length (number of C-atoms indicated), (a) surface tension y (N rrT1) against concentration c in solution, (b) Calculated surface excess / (mol rrT2) against concentration. 

Normal fatty acids were analyzed as their methyl esters on an SE-54 column. Hydroxylated fatty acids were analyzed... 

---