Fatty acids deuteration

Similarly, satisfactory results can be obtained with high molecular weight fatty acids by exchange deuteration with a metal catalyst in the presence of alkali and a suitable-peroxide promoter. ... 

The FT-IR technique using reflection-absorption ( RA ) and transmission spectra to quantitatively evaluate the molecular orientation in LB films is outlined. Its application to some LB films are demonstrated. In particular, the temperature dependence of the structure and molecular orientation in alternate LB films consisting of a phenylpyrazine-containing long-chain fatty acid and deuterated stearic acid (and of their barium salts) are described in relation to its pyroelectricity. Pyroelectricity of noncentrosymmetric LB films of phenylpyrazine derivatives itself is represented, too. Raman techniques applicable to structure evaluation of pyroelectric LB films are also described. 

RA and transmission techniques [3], and applied it to the studies of LB films of cadmium stearate [3], azobenzene-containing long-chain fatty acids and their barium salts [4], dipalmitoylphosphatidylcholine (DPPC) [5], and polyion complexes [6]. Furthermore, we explored the relationship between the molecular orientation evaluated by this method and pyroelectricity in alternating (noncentrosymmetric) Y-type LB films consisting of a phenylpyrazine-containing long-chain fatty acid and deuterated stearic acid and of their barium salts [7]. 

Other alternatives are the lyso-phosphatidylglycerol derivatives in which one of the fatty acid chains coupled to glycerol have been removed. Unfortunately, the phosphatidyl lipids are not available in fully deuterated form, and hence certain regions of the proton spectra will be covered by the glycerol protons. 

In 1933, Schoenheimer, who was medically qualified and had been working with Aschoff in the Pathology Institute in Freiburg, moved to Columbia University, New York, and was joined the next year by David Rittenberg. Rittenberg had just spent some time in Urey s laboratory in the Rockefeller Institute learning techniques for handling deuterium. Their first experiments concerned the metabolism of deuterated fatty acids in rats and the demonstration (see below) that 2H from heavy water was incorporated by the animals into fatty acids and cholesterol. 

Garbe L-A, Tressl R (2004) Metabolism of deuterated t/jreo-dihydroxy fatty acids in Saccha-romyces cerevisiae Enantioselective formation and characterization of hydroxylactones and y-lactones. Helv Chim Acta 87 180... 

The most important use of neutron diffraction in the general field encompassed by this book is in the study of alternating layers of deuterated and undeuterated films. At the time of writing, three papers have appeared on this topic. They are by Buhaenko et al. [56], Grundy et al. [57] and Stroeve et at. [58]. In the latter study, alternate layers of deuterated and undeuterated fatty acids were deposited and studied by neutron diffraction. Subsequently this ordered structure was destroyed by thermal diffusion and the gradual loss of order was monitored. The ordered structure is only destroyed at temperatures well above ambient. Applications of neutron diffraction to the study of lipid films at the air/water interface will be discussed in Chapter 8. 

The applications of PM-IRRAS also include fatty acids, phospholipids, and protein conformations. Desbat and co-workers reported on the variation of the dissociation of a Langmuir monolayer of arachidic acid at the air-water interface as a function of the subphase pH and for several cations (Cd2+, Ca2 +, Mg2 +, and Na+) with the help of the PM-IRRAS method [92]. Fig. 14 shows the PM-IRRAS spectra of Langmuir monolayer of deuterated arachidic acid in the presence of CdCb as a function of the subphase pH. At low subphase pH (pH = 3.5), the spectrum only presents absorption bands related to the acid form, i.e., the C = O stretching vibration (v(C = O)) and the OH bending (<5(0-H)) located at 1720 and 1270 cm respectively. The frequency position of the v(C = O) is characteristic of a hydrogen-bonded carbonyl group. As the subphase pH is increased, the arachidic acid is progressively deprotonated to... 

Polar phospholipids are investigated best in the spectral region between 3100 and 700 cm. The infrared and Raman spectra of lipids may be divided into bands which originate from molecular vibrations of the acyl chains, of the head group, and of the interfacial region. The characteristic wavenumbers of different groups are tabulated in the references listed above. The IR and Raman bands of specifically deuterated fatty acids and completely deuterated acyl chains have also been characterized (Mendelsohn and Maisano, 1978 Lee et al., 1984 Devlin and Levin, 1990). 

Mendelsohn, R., Sunder, S. and Bernstein, H. J. Deuterated fatty acids as Raman spectroscopic probes of membrane stmcture. Biochimica et Biophysica Acta 443 613-617, 1976. 

Stockton, G. W. and Smith, I. C. P. (1976). A deuterium NMR smdy of the condensing effect of cholesterol on egg phosphatidylcholine bilayer membranes. 1. Per-deuterated fatty acid probes. Chem. Phys. Lipids 77 251. 

The use of neutron diffraction provides structural information about fats in hquid and crystalline states through interactions of neutrons with atomic nucleus that is different from the information provided by X-ray diffraction. Neutron diffraction studies with selective deuteration of glycerine and fatty acid chains of a TAG indicated nematic-type liquid crystal organization of the TAG molecules in the liquid phase (21, 22). 

Whereas in case of liposomes the nonsymmetric deuteration of the alkeneic bond in the unsaturated fatty acids could be assisted by the liquid cage around the catalyst, in the homogeneous solution of itaconic acid or its esters multideuter-ation is facilitated by the coordination of the carboxylic group or the ester carbonyl [84]. 

A quantity of fat was hydrolyzed to various fatty acids, one of which is palmitic acid. A 0.216 g sample of deuterated palmitic acid was added to the mixture, a sample of pure palmitic acid isolated, and its isotope content determined in the mass spectrometer. If the added palmitic acid was 21.5% deuterated, and the final palmitic acid was 2.75% deuterated, how much palmitic acid was present initially [The deuterated compound may be assumed to have the same molecular weight as the undeuterated.]... 

In multicomponent systems difficulties arise from the overlapping of C-H features due to chemically different lipids, or in hpid-protein arrays, from protein C-H stretching bands. In these systems it becomes impossible to monitor a single lipid component. Mendelsohn et al. [64] showed how this problem csai be overcome by the use of deuterated components. They inserted a completely deuterated fatty acid into a model membrane system and followed the C-D stretching vibrations in the spectral window 2000-2220 cm which is uncluttered by modes from other components. As the membrane passed through a gel-liquid crystal transition the line-width of the C-D stretching vibrations of the bound fatty add was found to be a sensitive probe of membrane polymethylene chain order. 

Nuclear Magnetic Resonance Spectroscopy. Like IR spectroscopy, NMR spectroscopy requires little sample preparation, and provides extremely detailed information on the composition of many resins. The only limitation is that the sample must be soluble in a deuterated solvent (e.g., deuterated chloroform, tetrahydro-furan, dimethylformamide). Commercial pulse Fourier transform NMR spectrometers with superconducting magnets (field strength 4-14 Tesla) allow routine measurement of high-resolution H- and C-NMR spectra. Two-dimensional NMR techniques and other multipulse techniques (e.g., distortionless enhancement of polarization transfer, DEPT) can also be used [10.16]. These methods are employed to analyze complicated structures. C-NMR spectroscopy is particularly suitable for the qualitative analysis of individual resins in binders, quantiative evaluations are more readily obtained by H-NMR spectroscopy. Comprehensive information on NMR measurements and the assignment of the resonance lines are given in the literature, e.g., for branched polyesters [10.17], alkyd resins [10.18], polyacrylates [10.19], polyurethane elastomers [10.20], fatty acids [10.21], cycloaliphatic diisocyanates [10.22], and epoxy resins [10.23]. 

The synthesis of a novel cyclopropyl analog of arachidonic acid [7] via a convergent synthesis that employed methyl (lR,25)-2-formylcyclopropane-carboxylate in conjunction with the ylide from (3Z,6Z)-pentadeca-3,6-dienyl(triphenyl)-phosphonium iodide was reported (62). A new approach to cyclopropene fatty acids has been developed for the synthesis of methyl sterculate [8] and methyl 2-hydroxy-sterculate this involves the 1,2-deiodination of 1,2-diiodocyclopropanes with butyllithium at low temperature (63). The synthesis of deuterated cyclopropene fatty esters structurally related to palmitic and myristic acids has been reported (64). 

Numerous well-known methods exist for analyzing fimctional groups in a fatty acid chain. These methods include deuteration, hydrogenation, epoxidation, hydrox-ylation, and silylation. Ozonolysis, although strictly speaking not a derivatization because the fatty acid chain is cleaved and the cleavage products analyzed, can also... 

Analysis of Labeled Acyl Groups. Deuterated branched chain amino acids were all incorporated at extremely high rates into sugar ester acyl groups, an indication of the active nature of this pathway. In some instances the amount of deuterium labeled fatty acids exceeded (146%) that of the unlabeled material remaining on the leaf surface (10-20% of the original amount of glucose ester). GC/MS data for labeled 3-methylbutyrate from the incubation of [dio] Leu are shown in Fig. 2. As... 

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