Myristic acid, 439 Table

The transfer of phosphatidylcholine from monolayer to vesicles catalyzed by phosphatidylcholine transfer protein shows remarlcable differences for the positional isomers (23). The PC transfer protein acts as a specific carrier of PC between membrane interfaces. This protein has a recognition site for the phosphorylcholine headgroup and binding sites for the sn-1 and sn-2 fatty acyl chain. Lysophosphatidylcholine is not transferred. It was found that the protein transferred C10 0/C18 l PC twice as fast as C18 l/C10 0 PC. Similar differences in rate were observed for C12 0/C18 l PC and C18 l/C12 0 PC but not for isomers carrying myristic acid (Table I). 

N-Myristoylation is achieved by the covalent attachment of the 14-carbon saturated myristic acid (C14 0) to the N-terminal glycine residue of various proteins with formation of an irreversible amide bond (Table l). 10 This process is cotranslational and is catalyzed by a monomeric enzyme called jV-myri s toy 11ransferase. 24 Several proteins of diverse families, including tyrosine kinases of the Src family, the alanine-rich C kinase substrate (MARKS), the HIV Nef phosphoprotein, and the a-subunit of heterotrimeric G protein, carry a myr-istoylated N-terminal glycine residue which in some cases is in close proximity to a site that can be S-acylated with a fatty acid. Functional studies of these proteins have shown an important structural role for the myristoyl chain not only in terms of enhanced membrane affinity of the proteins, but also of stabilization of their three-dimensional structure in the cytosolic form. Once exposed, the myristoyl chain promotes membrane association of the protein. 5 The myristoyl moiety however, is not sufficiently hydrophobic to anchor the protein to the membrane permanently, 25,26 and in vivo this interaction is further modulated by a variety of switches that operate through covalent or noncovalent modifications of the protein. 4,5,27 In MARKS, for example, multiple phosphorylation of a positively charged domain moves the protein back to the cytosolic compartment due to the mutated electrostatic properties of the protein, a so-called myristoyl-electrostatic switch. 28 ... 

Draw the structure of glycerol myristate, a fat made from glycerol and three myristic acid molecules (see Table 24.3). 

It is important to bear in mind when discussing the effect of dairy fat in association to heart disease that dairy products contain many different saturated fatty acids that do not exert the same biological response in terms of, for example, cholesterol levels. The saturated fatty acids in milk fat include shorter and medium chain fatty acids (2 0-10 0), lauric acid (12 0), myristic acid (14 0), palmitic acid (16 0), and stearic acid (18 0). Other fatty acids in milk fat are oleic acid (18 1) and linoleic acid (18 2n-6) as indicated in Table 1.2. 

The activities of the immobilized lipase components in ester synthesis have also been tested. Myristic acid was esterified with propanol, isopropanol, and oleic alcohol, respectively (Table X). 

Myristic acid was purchased from Sigma (St Louis, MO) and ethanol (99.85 %) from Prolabo (France). Ultra pure carbon dioxide (99.995 %) was purchased from Airgaz (France). The lipase (E C. 3.1.1.3.) was a commercial enzyme from Mucor miehei kindly supplied by Novo Nordisk (Denmark). This lipase (Lipozyme TM) is immobilized on Duolite A568 (Rohm and Hass). The resin particles have a size comprised between 300 to 600 pm. In order to see if a phenomenon of internal mass transfer occurs during the enzymatic esterification, we sieved the support into different size series. The average granulometry was determined by Coulzer Sizer method (Table 1). 

Brazil nuts Bertholletia excelsa) are widely consumed but are produced mainly in South America, with total world production estimated to be about 20,000 metric tons. Bolivia, Brazil, and Peru are the main Brazil-nut-producing nations (59). Brazil nuts are traded mainly in the form of kernels (i.e., shelled) and are used in confectionery, bakery, and health foods. Brazil nuts contain 66-69% lipid, 14.3% protein, 12.2% carbohydrate, 3.5% ash, and 3.5% water (w/w) (1, 60). Brazil nut oil is used in the areas it is produced as cooking oil and is being promoted on the export market (59). As the export value of shelled BrazU nuts is so high, usually only defective Brazil nuts (cracked and partially oxidized) are extracted for their oils that can result in oils with acid values and peroxide values as high as 5.9-mg KOH/g oil and 7.6-meq oxygen/kg oil, respectively (61). The fatty acid composition of BrazU nut oil includes 29 8% oleic acid, 30-61% linoleic acid, 14—15% palmitic acid, 6-8% stearic acid, and 0.5% myristic acid (60,62) (Table 7). 

Watermelon seed oil was prepared and evaluated for its physicochemical properties (22, 23). The seed oil consisted of 59.6% linoleic acid (18 2n-6) and 78.4% total unsaturated fatty acids (Table 4). The predominant fatty acid in the oil was linoleic acid, which was followed by oleic, palmitic, and stearic acids. Linolenic, palmitoleic, and myristic acids were minor constituents. The refractive index, acid value, peroxide value, and free fatty acids of watermelon seed oil were determined to be 1.4696 (25°C), 2.82 (mg KOH/g oil), 3.40 (mequiv oxygen/kg oil), and 1.41 (% as oleic acid), respectively. The saponification value of watermelon seed oil was 201 (mg KOH/g oil), and its iodine value was 115 (g iodine/100-g oil), which was significantly higher than pumpkin at 109 (g iodine/lOO-g oil) (22, 23). 

Dates Phoenix dactylifera L.) are popular in most Middle Eastern countries and serve as a major source of food and nutrients (51, 52). Oil contents and fatty acid profiles of date seeds may vary among individual varieties. Date seeds contained 20-24% total fat (49). Oleic acid was the primary fatty acid in the date seed oil and had a concentration of 43.5 5% of total fatty acids. This was followed by lauric (12 0), myristic (14 0), palmitic (16 0), linoleic (18 2n6), capric (10 0), and stearic (18 0) acids along with trace amounts of other fatty acids (Table 7). Date seed oil may serve as an excellent dietary source of oleic acid with a minor amount of linoleic acid. 

The basic fish oil (27) also included a generous amount of saturated fatty acids. As can be seen from Figure 5 and Table 1, the saturated fatty acids are dominated by the 16 0 (palmitic acid), usually accompanied by about half as much or less of 14 0 (myristic acid) and much less of 18 0 (stearic acid). Usually the saturated fatty acid totals are at least 20%, especially as the odd chain (15 0, 17 0) and methyl-branched (iso, anteiso, pristanic, phytanic) fatty acids (compare Figure 4) are sam-rated and will total around 2-3%. An unsaturated peak that is often observed is 17 ln-8, which is roughly equal to 17 0. The details of these peaks are discussed in other publications, but those researchers attempting modern open-tubular gas chromatography analyses should be aware of their presence and influence on peak identification and quantitation. As can be seen from Figure 6, there is an... 

Although not included in any pharmacopeias, a specification for myristic acid is contained in the Food Chemicals Codex (FCC) and in the Japanese Pharmaceutical Excipients (JPE), see Table I. 

Table I Food Chemicals Codex and Japanese Pharmaceutical Excipients specifications for myristic acid.

When a monolayer of myristic acid spread on 0.01N HC1 was used over the same pressure range (5 dynes/cm), the change in pressure on compression and expansion was independent of the position of the wet-table blade from the moving barrier. 

MCT oils are usually made by esterification of distilled C8 and Cio fatty acids, derived from the acid-oil byproducts of lauric oil refining or from high pressure splitting of lauric oils. Another route is the direct molecular distillation of lauric oils. The C8 to Ci0-depleted oils are then even richer sources of lauric and myristic acids for the oleochemical and soap industries. Examples of MCT oils used in dietetic chocolate spread are shown in Table 6.39. 

The spreading-pressure of mjnistic add CuHjj.COjH on water has been measured at 14.5 C by Adam and Jessop (Proc. Roy. Soc. 1926, 110, 423, and private communication from Adam to Wolfenden), Some of their measurements are given in table 1. The first column gives the mass of myristic acid, the second column the length of the film, and the third column the force on the float. The width of the trough was 14.0cm and the efiective width of the barrier was 12.33 cm. 

Table 8.25 Best experimentally observed heats of fusion according to Timms (1978) (C = capric acid, L = lauric acid, M = myristic acid, P = palmitic acid, S = stearic acid and O = oleic acid)...

The second category of prodncts contains the same ingredients as above but with fatty acids such as lauric, myristic, or oleic acids (Table 6.6) [1]. 

By way of example. Table 7.1 presents values of qic le t>nd Alc le the LC —> LE transition in monolayers of myristic acid, (CH3 - (CH2)i5 - COOH), at the air/ water interface. The main conclusions from these data are that heat is required to disrupt energetically favorable interactions between the surfactant molecules when releasing th from the condensed state. This is accompanied by an increased entropy of the monolayer. Furthermore, the tanperature dependence of q, at con-... 

Reduction of the ACP-bound acetoacetate yields D-jff-hydroxybutyryl-ACP from which croto-nyl-ACP is formed by the elimination of water. By the subsequent reduction butyryl-ACP is obtained from which the butyryl residue is transferred to CoA, releasing the SH-group of panto-theine which again reacts with a molecule of malonyl CoA. Butyryl CoA, like acetyl CoA, may react with the peripheral, acyl-binding SH-group of the synthase and subsequently with the malonyl residue. In the following reactions caproic acid is formed from which caprylic, capric, lauric, myristic, palmitic, stearic, and arachidonic acid (Table 26) are formed. The specificity of the enzymes involved as well as other factors such as compartmentalization, stop chain elongation at about 10-20 C-atoms. 

The products are glycerol and three carboxylate ions. Using Table 26.1, we can identify these carboxylate ions as the conjugate bases of palmitic acid, myristic acid, and linoleic acid. 

Raymond and Pandis in two separate smdies experimentally determined the CCN activities of various single-component organic particles [169] and internally mixed, multicomponent particles [168] such as glutaric acid, adipic acid, pinonic acid, glutamic acid, leucine, cholesterol, pinic acid, norpinic acid, hexadecane, hexadecanol, myristic acid, palmitic acid, and stearic acid with sodium chloride and ammonium sulfate in the latter smdy. Their results are sununarized in Table 8 and Fig. 5. 

The ganglioside fatty acids in TSD consist of 85% stearic acid, 4.5% myristic acid, 6.6% arachidonic acid, and 1.6% behenic acid (Klenk et al. 1963). The nomenclature of gangliosides is outlined in table 1. 

Myristic acid (3-1) is a common Hpid component of most Hving organisms. It usually represents about 1 -2% of total fatty acids and is present at higher levels in milk fat (10%) and coconut and pahn kernel oils (14-21%). The fat of farm animals, especially of pigs and ruminants, contains long chain saturated fatty acids, palmitic and stearic acids. The content of these fatty acids is lower in the depot fat of commercially reared birds (Table 3.10). 

The liver fatty acids (Table 9), like the serum fatty acids, reflected the influence of dietary coconut oil. The control liver lipids contained less lauric and myristic acids than did the liver lipids of the test groups. 

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