Palmitic acid derivative

Figure 17.20 An azido-palmitic acid derivative can be added to cells to obtain palmitoylated proteins that contain an azide group able to participate in the Staudinger ligation reaction. Biotinylation of these post-translationally modified sites then can be done in vivo using a biotin-phosphine reagent.

The results of these experiments have been recalculated from the data of Zabin and Mead (1953, 1954) and Sprinson and Coulon (1954) and are presented in Table 1. It is immediately apparent from this data that acetate labelled in either the one or two positions gives rise exclusively to the hydrocarbon portion of the sphingosine. Degradation of the palmitic acid derived from the sphingosine labelled with acetate-2-shows that carbon 4 is 3 to 5 times richer in than carbons 3 or 5. This is consistent with the pattern observed during fatty acid synthesis... 

Bromophenol blue (3.0...4.6) aliphatic carboxylic acids [225 — 228] malonic and lactic acids [229] palmitic and lactic acids [230] malonic, glycolic, malic, citric, tartaric, ketoglutaric, galacturonic and oxalic acids [196] dicarboxylic acids, succinic acid [231] indoleacetic acid, trichloroacetic acid [232] palmitic acid, palmityl- and stearyllactic acid [223] benzoic, sorbic and salicylic acid [234] metabolites of ascorbic acid [235] chloropropionic acid [236] oligogalacturonic acids [237] amino acids, hydrocarbons, mono-, di- and triglycerides [238] xylobiose, xylose, glucose and derivatives [239] sugar alcohols [91] toxaphene [240]... 

The imminium chloride formed was transformed, in-situ, into the corresponding carboxyhc acid derivative, this was added to a solution of cellulose in LiCl/DMAc. Palmitic, stearic, adamantane-1-carboxylic, and 4-nitrobenzoic acids were employed. The DS of the corresponding esters increased as a function of increasing the ratio oxalyl chloride/AGU. The solubihty of the products obtained in aprotic solvents was tested GPC results have indicated negligible degradation of the polymer [200]. 

Biosynthesis of Unsaturated Fatty Acids. In the mammalian tissues, the forma-tion of monoene fatty acids is only possible. Oleic acid is derived from stearic acid, and palmitooleic acid, from palmitic acid. This synthesis is carried out in the endoplasmic reticulum of the liver cells via the monooxigenase oxidation chain. Any other unsaturated fatty acids are not produced in the human organism and must be supplied in vegetable food (plants are capable of generating polyene fatty acids). Polyene fatty acids are essential food factors for mammals. 

Macrolide aggregation pheromones produced by male cucujid beetles are derived from fatty acids. Feeding experiments with labeled oleic, linoleic, and palmitic acids indicate incorporation into the macrolide pheromone component [ 117 ]. The biosynthesis of another group of beetle pheromones, the lactones, involves fatty acid biosynthetic pathways. Japonilure and buibuilactone biosynthesized by the female scarab, Anomalajaponica, involves A9 desaturation of 16 and 18 carbon fatty acids to produce Z9-16 CoA and Z9-18 CoA,hydroxylation at carbon 8 followed by two rounds of limited chain shortening and cyclization to the lactone [118]. The hydroxylation step appears to be stereospecific [118]. 

The most common major components of cutin are derivatives of saturated C16 (palmitic) acid and unsaturated C18 acids (Fig. 4). The major component of the C16 family of acids is 9- or 10,16-dihydroxyhexadecanoic acid (and some mid-chain positional isomers), with less 16-hydroxyhexadecanoic acid and much smaller amounts of hexadecanoic acid. In some cases other derivatives are significant constituents. For example, in citrus cutin 16-hydroxy-10-oxo-C16 acid, and in young Vicia faba leaves 16-oxo-9 or 10-hydroxy C16 acid are significant... 

Figure 11.9 Pyrogram of a paint sample collected from sixteenth century wall paintings in the Messer Filippo cell of the tower in Spilamberto, Italy. Pyrolysis was performed with a micro furnace pyrolyser, at 600°C, in the presence of HMDS. 1, Carbohydrate pyrolysis products 2, lauric acid 3, suberic acid 4, levoglucosane 5, azelaic acid 6, miristic acid 7, hexadecanenitrile 8, palmitic acid 9, octadecanenitrile 10, oleic acid 11, stearic acid. TMS derivative [74]...

Figure 22.20 The NHS ester derivative of palmitic acid may be used to couple antibody molecules through amide bonds. These complexes then may be incorporated into liposomes.

This structure shows a triglyceride with three identical saturated fatty acids. Tripalmitin, in which all fatty acids are palmitic acid (n = 14), provides one example of a fat. Triolein is an oil containing only oleic acid moieties esterified to glycerol. In contrast to these two examples, it is by no means necessary that the three fatty acid groups be derived from only one fatty acid. For example, we might have a triglyceride that contains one saturated fatty acid, say palmitic acid, one monounsaturated fatty acid, say oleic acid, and one polyunsaturated fatty acid, perhaps arachidonic acid. 

An early synthesis of A5-palmitoy]-.S -[2,3-bis(palmitoyloxy)propyl]cysteine employed cysteine methyl ester, however, this leads to difficulties in the saponification step of the tri-palmitoylated residue. 96 The optimized procedure, in which the cystine di-fert-butyl ester is used, 90 is outlined in Scheme 6 after N-acylation with palmitoyl chloride, the ester is reduced to the cysteine derivative for S-alkylation with l-bromopropane-2,3-diol to yield chirally defined isomers if optically pure bromo derivatives are used. Esterification of the hydroxy groups is best carried out with a 1.25-fold excess of palmitic acid, DCC, and DMAP. The use of a larger excess of palmitoyl chloride is not recommended due to purification problems. The diastereomeric mixture can be separated by silica gel chromatography using CH2Cl2/EtOAc (20 1) as eluent and the configuration was assigned by comparison with an optically pure sample obtained with 2R)- -bromopropane-2,3-diol. 

The principal monoenoic acids, oleic (C18 1) and palmitoleic (C16 1), are derived from blood lipids but about 30% of these acids are produced by microsomal enzymes (in the endoplasmic reticulum) in the secretory cells by desaturation of stearic and palmitic acids, respectively ... 

In contrast to the anaerobic pathway found in E. coli, the aerobic pathway in eukaryotic cells introduces double bonds after the saturated fatty acid has been synthesized. Stearoyl-CoA (18 0) is the major substrate for desaturation. Stearic acid is made by the fatty acid synthase as a minor product, the major product being palmitic acid, and is activated to its CoA derivative by acyl-CoA synthase. In eukaryotic cells an enzyme complex associated with the endoplasmic reticulum desaturates stearoyl-CoA to oleoyl-CoA (18 1A9). This remarkable reaction requires NADH and 02 and results in the formation of a double bond in the middle of an acyl chain with no activating groups nearby. The chemical mechanism for desaturation of long-chain acyl-CoAs remains unclear. 

Despite the large variety of potential fatty acid components in natural-occurring phosphodiglycerides, only three major fatty acid derivatives of synthetic phospholipids are commonly used in liposome preparation (1) myristic acid (w-tetradecanoic acid containing 14 carbons), (2) palmitic acid (w-hexadecanoic acid containing 16 carbons), and (3) stearic acid (w-octadccanoic acid containing 18 carbons) (Fig. 334). 

The nomenclature for associating individual fatty acid groups with particular phos-phodiglyceride derivatives is straightforward. For instance, a phosphatidic acid derivative that contains two myristic acid chains is commonly called dimyristoyl phosphatidic acid (DMPA). Likewise, a PC derivative containing two palmitate chains is called dipalmitoyl phosphatidyl choline (DPPC). Other phosphodiglyceride derivatives are similarly named. 

FIGURE 6.6 A triglyceride derivative of chlorambucil, where the chlorambucil attached to the 2-position, and palmitic acid to positions 1 and 3 of the triglyceride. (From Stella, VJ. and Pochopin, N.L. Lymphatic Transport of Drugs, Charman, W.N. and Stella, V.J., Eds., CRC Press, Boca Raton, 1992, p. 181. With permission.)... 

A (approximately 13.6 kDa) increases passage across the BBB by almost ninefold. Of the three fatty acid derivatives analyzed (myristic, palmitic, and stearic), the stearic modification had the greatest effect. The most likely mechanism for the entry of fatty acylated polypeptides to the brain is adsorptive endocytosis. 

Thus, combination of one acetate starter unit with seven malonates would give the Ci6 fatty acid, palmitic acid, and with eight malonates the Ci8 fatty acid, stearic acid. Note that the two carbons at the head of the chain (methyl end) are provided by acetate, not malonate, whilst the remainder are derived from malonate, which itself... 

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