Acyl lipid

YOSHIDA H, shigezaki J, TAKAGi s and KAJIMOTO G (1995) Variations in the composition of various acyl lipids, tocopherols and lignans in sesame seed oils roasted in a microwave oven , J Sci Food Agric, 68 (4) 407-16. 

S. N. Dudd, M. Regert and R. P. Evershed, Assessing microbial contributions to absorbed acyl lipids during laboratory degradations of fats and oils and pure triacylglycerols absorbed in ceramic potsherds. Organic Geochemistry, 29, 1345 1354 (1998). 

Raven, A. M., van Bergen, P. F., Stott, A. W., Dudd, S. N., and Evershed, R. P. (1997). Formation of long-chain ketones in archaeological pottery vessels by pyrolysis of acyl lipids. Journal of Analytical and Applied Pyrolysis 40 267-285. 

In asymmetrically acylated lipid A, the four primary hydroxy-fatty acids possess the same chain length of 14 carbon atoms [thus far, with one exception (193b), only 14 0(3-OH) was identified]. 

In bioactive materials, enzymatic reactions (nos. 1-3 in Table 16.1) are inhibited by homogenising the sample in the presence of calcium ions that precipitate the enzymes [12]. A lower pH value enhancing reactions 4-7 should be buffered and a higher temperature is avoided by distilling off the volatiles under vacuum. Samples containing hydroperoxides derived from unsaturated acyl lipids are sensitive to temperatures above 40 °C (no. 8). 

Similar experimental results and conclusions have been reported by Hawke and Alexander (ref. 117) and by Hawke and Parts (ref. 118). These authors also point out that these saturated acyl lipid monolayers need to be in the close-packed (i.e., laterally compressed) condition before significant reduction in gaseous diffusion is observed (ref. 117,118 see also Sections 1.3.1 and 7.6). 

Fig. 6.4 shows the IT-A curves obtained for microbubble-surfactant monolayers on a variety of aqueous subphases. In order to compare Il-A measurements for monolayers which would contain essentially only glycopeptide-acyl lipid complexes, the data plotted in Fig. 6.4 include only Il-A measurements made during the expansion phase (following an initial compression to at least 23 dyne/cm). Judging from the fact that subphases of either distilled water, 0.1 M HC1 (pH 1.1), 0.1 M NaOH (pH 12.3), or 0.1 M NaF... 

GLYCOPEPTIDE ACYL LIPID AREA RATIO AND ASSOCIATION OF COMPLEXES WITHIN MONOLAYERS... 

Interestingly, the FIA-FI plots for microbubble-surfactant monolayers on subphases other than distilled water provide indirect evidence for induced association of the glycopeptide-acyl lipid complexes themselves. It can be seen from Fig. 6.5 that the monolayer data obtained on subphases of 0.1 M NaF, 0.1 M HC1,... 

Fig. 7.1 shows a typical H-NMR spectrum obtained with the partially purified, microbubble surfactant mixture prior to monolayer formation. For comparison, Table 7.1 gives the chemical-shift data for the proton resonances that can be readily identified in the 1 H-NMR spectra of long-chain acyl lipids (ref. 395-401). 

Fig. 10.2 Structures of the minor hexa-acyl lipid A molecular species found in H. pylori smooth-form LPS (left) and the tetra-acyl lipid A species found in H. pylori rough- and predominating in smooth-form LPS (right) (Moran et al., 1997). One 3-deoxy-D-man ooct-2-ulosonic acid residue, as occurs in the H. pylori core OS, is shown attached to the 6 -position of lipid A. The numbers in circles refer to the number of carbon atoms in the acyl chains. Compared to the hexa-acyl minor species, the tetra-acyl molecular species lacks 4 -phosphate and is substituted at position-1 by phosphoethanolamine...

MS analysis of lipid A from laboratory-adapted PA strains grown in rich medium reveals a dominant ion species (m/z) of mass 1447 (Fig. 11,2a), corresponding to a penta-acylated molecule. This is the major structural form of lipid A isolated from laboratory-adapted PA strains (PAOl, PAK, PAM) grown in rich medium (Bhat et al., 1990 Ernst et al., 1999 Moskowitz et al., 2004). Additional lipid A species observed by MS are dependent on growth conditions (concentration of magnesium or iron, low pH, and reduced oxygen levels), and the strain from which the lipid A was isolated (Goldman et al., 1988). In PA strains, penta-acylated lipid A species are usually most abundant however, specific lipid A structures often differ between CF (m/z 1447, Fig. 11.2a) and non-CF isolates (m/z 1419, Fig. 11.2d). 

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