Palmitic acid structure

Palmitic acid, structure of, 1062 Palmitoleic acid, structure of, 1062 PAM resin, solid-phase peptide synthesis and, 1037 Para (m), 519 Paraffin, 91 Parallel synthesis, 586 Parent peak (mass spectrum), 410 Partial charge, 36 Pasteur, Louis, 297, 307... 

Spermaceti, a fragrant substance from sperm whales, was much used in cosmetics until it was banned in 1976 to protect the whales from extinction. Chemically, spermaceti is cetyl palmitate, the ester of cetyl alcohol (u-ClrtH33OH) with palmitic acid. Draw its structure. 

In the x-ray structure of rhodopsin, an amphipathic helix runs parallel to the membrane from the intracellular end of TM-VII beneath the seven-helical bundle to the other side of TM-I and TM-II. At this point, one or more Cys residues are often found and are known to be subject to a dynamic posttranslational modification with palmitic acid residues. Like the phosphorylation event, the palmitoylation process appears to be dynamically regulated by receptor occupancy and is also involved in the desensitization phenomenon. The two posttranslational modifications can influence each other. For example, the conformational constraint induced by palmitoylation may alter the accessibility of certain phosphorylation sites. Like the phosphorylation process, the functional consequences of palmitoylation also appear to vary from receptor to receptor. 

Soaps are composed of sodium salts of various fatty acids. These acids include those with the general structure CH3-(CH2) -COOH where n = 6 (caprylic acid), 8 (capric acid), 10 (lauric acid), 12 (myristic acid), 14 (palmitic acid), and 16 (stearic acid). Oleic acid (CH3-(CH2)7-CH=CH-(CH2)7-COOH) and linoleic acid (CH3-(CH2)4-CH=CH- H2-CH=CH-(CH2)7-COOH) are also common soap ingredients. These sodium salts readily dissolve in water, but other metal ions such as Ca2+ and Mg2+ form precipitates with the fatty acid anions. For example, the dissolution of the sodium salt of lauric acid and the subsequent formation of a precipitate of the lauric acid anion with calcium ion is given by... 

Figure 13.16.4 The molecular structure of the mixed fatty acid palmitodiolein, which is triglyercide of two esters of oleic acid and one of palmitic acid.

Figure 11.1 Structures of commonly occurring saturated fatty acids (i) myristic acid, Ci4 o (ii) palmitic acid, C s-.o (iii) stearic acid, Ci8 0.

Figure 12.2 Structure of waxes. The general structure of a wax is shown in which n and m are usually between 8 and 18. The structure of hexadecyl hexadecanoate (cetyl palmitate), a wax found in sperm whale oil, is shown. This is an ester of hexadecanoic (palmitic) acid and hexadecanol (cetyl alcohol).

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. 

It is pertinent to note here the observed increase in the value of the structure-sensitive parameter p from 1 to 2. This implies that the architecture of the sodium caseinate aggregates, as modified by interaction with the surfactant, becomes generally more open, despite the inferred collapse of their constituent protein nanoparticles. In contrast, a shell-like aggregation structure can be inferred for the self-assembly of sodium caseinate as a result of its interaction with the non-ionic surfactant PGE (this surfactant is based on a mixture of the esters of stearic and palmitic acids in chemical combination with polyglycerol (Krog, 1997)). 

Since the amounts of fatty acids available for acylation during the biosynthesis of milk TGs affect their placement, feeding protected oils can be expected to alter the structure of the TGs. The data of Christie and Clapperton (1982) show that total and therefore all positional 18 2s are higher than in normal milk. Palmitic acid (16 0) decreases reciprocally. 

Dimick, P. S., McCarthy, R. D. and Patton, S. 1965. Structure and synthesis of milk fat. VIII. Unique positioning of palmitic acid in milk fat triglycerides. J. Dairy Sci. 48, 735-737. 

There are two isomeric fat molecules whose components are glycerol, one palmitic acid, and two stearic acids (see Table 24.3). Draw the structures of both, and explain how they differ. 

CH2) 1470 Lipids Splitting occurs for orthorhombic crystalline structures. In some cases, this band can be used to identify crystalline regions of fatty acids, such as palmitic acid. 

Fig. 1. Structural representations and fidelity of synthesis of lipopeptide and nonlipidated peptides. (A) Structure of the lipopeptide vaccines palmitic acid, Pam. (B) HPLC chromatograms of purified lipopeptides. Analysis by HPLC was performed on a Waters HPLC System using a Vydac C4 column with 0.1% TFA in water and 0.1% TFA in acetonitrile as a gradient mobile phase. A flow rate of 1 mL/min was used at a gradient of 2%/min. Chromatograms were obtained by the detection of absorbance at a wavelength of 214 nm. (C) Mass spectral analysis of purified lipopeptides. Lipopeptides were analyzed by mass spectrometry using an Agilent 1100 Series LCM/MSD ion trap.

Analysis of the primary protein structure of the human 5-HT1B receptor reveals a putative site for palmitoylation, i.e., a cysteine residue located in the short carboxyl tail of the receptor (141). A recombinant c-myc epitope-tagged 5-HT1B receptor was expressed in Sf9 insect cells and palmitoylation of the receptor was demonstrated by metabolic labeling of the cells with [3H]palmitic acid. 

---