Lipid methylation

In water-suppressed muscle spectra, contributions of lipids, methyl and methylene groups of creatine (Crs, Cr2), trimethylammonium-containing compounds (TMA), including signals from carnitine (Ct), choline (Cho), and taurine (Tau) are well observable as demonstrated in Fig. 15. Furthermore, small signals of histidine protons of carnosine (Cs) can be sometimes identified... 

The red-sided garter snake pheromone components were isolated by hexane extraction of the skin lipids of sacrificed snakes. Female snakes yielded more total lipid than males (38.4 versus 8.4mg snake-1)80 Initial fractionation on an activity III alumina column gave a fraction (eluted with 98 2, hexanes ethyl ether) that was attractive to courting males. NMR and infrared (IR) spectra of this fraction were suggestive of the presence of methyl ketones, straight chain alkyl lipid subunits, and Z-alkenes. GC—MS analysis, including extensive consideration of the fragmentation of the electron impact MS data, led to the identification of a family of relatively nonvolatile (C29—C37) lipid methyl ketones. Specifically, the individual components of a mixture of saturated and monounsaturated methyl ketones 18—30 were identified. 

Fig. 6 Methyl trap hypothesis 5,10-Methylenetetrahydrofolate is reduced to 5-methyltetiahy-drofolate in an irreversible reaction. When vitamin Bn is deficient, methyl groups are trapped as 5-methyltetrahydrofolate, resulting in decreased substrates for DNA synthesis and neural lipid methylation. MTHFR, methylenetetrahydrofolate reductase DHFR, dihydrofolate reductase MS, Methionine synthase TS, thymidylate synthase SAM, S-adenosyl-methionine dUMP, deoxyuridine 5 -monophosphate dTTP, deoxythymidine 5 -monophosphate...

With increasing temperature all the lipidic methyl and methylene group peaks sharpen and increase in intensity. This is consistent with a general reduction in the plasma viscosity and increased motional freedom of the lipoprotein particles which also significantly increase the 2D HMQC... 

Lipids Methyl oleate, Methyl stearate, Methyl arachidate, Methyl behenate, Methyl lignocerate Vydac 35-44 p Methanol-water (90 10)... 

Fig. 28. CP-MAS (left) and DD-MAS (right) NMR spectra of [S-i QAla-labeled W80L (A and D), W12L (B and E), and wild-type (C and F). The intense asterisked peak at 19.8 ppm for W80L and W12L is ascribed to the lipid methyl group. Reproduced with...

Saturated biodiesel fraction Biodiesel production from animal lipids Methyl esters of fatty acids Cupriavidus necator [47,48]... 

Fig. 4.7. Partial GC chromatogram of total beef heart lipids methylated using an acid- (upper) or a base-catalyzed (lower) procedure.The acid-catalyzed methylation product included dimethylacetals (DMA) from plasmalogenic lipids and alk-l-enyl methyl ethers (AME) produced by loss of methanol from the DMA during GC analysis.

The numerical determination of the value quantities as a function of time allows explaining the chemical reason of the antioxidant s effectiveness. Also the value method has been used to analyze the mechanisms for the liquid phase oxidation of ethylbenzene and model lipids methyl linoleate, in the presence of antioxidants in the reaction mixture - butylated hydroxytoluene and a-tocopherol, respectively. The dominant steps responsible for the antioxidant and pro-oxidant properties of cMn reaction inhibitors are identified. 

Using as an example the kinetic model of peroxidation for a model lipid, methyl linoleate, in the presence of a bioantioxidant, a-tocopherol, the capability of value analysis for revealing individual chemical steps responsible for one or another manifestation of the chemical action of antioxidants was demonstrated. 

CoASH for 15 minutes. Labeled microsomes were separated into equal aliquots for assays. Assay reactions contained ImM reduced dinucleotide and were allowed to proceed 1-3 h prior to terminating by extracting with 2 vol chloroform methanol (2 1) and addition of a few drops of 1 M oxalic acid. Chlorofom extracts were blown to dryness with N2 and lipids were methylated by first adding 0.5 ml sodium methoxide (18 mg/ml) in methanol for 30 min and then adding ethereal diazomethane. In order to ensure complete recovery of lipids, methyl esters were extracted with 2 vol of chloroform water was added for phase separation. Chloroform extracts were concentrated to a volume of 50 pi for analysis on silica gel TLC in hexane diethyl ether acetic acid (85 15 1). 

The effect of different pH upon lipid methylation has been examined only up to a value of 8.8, although it would be important with successive studies to extend the range of pH up to higher values, where pH optima have been found, at least for other tissues, for the second methyl transferase 13 On the other hand, as known, SAM is unstable above pH 9 ... 

The data presented in Fig.3-5 show that the methyl transferase v4iich converts Ptd-ethanolamine to PME in brain microsomes possesses an optimum pH value at 8.2, and that probably a second peak of maximal activity aroimd 7 is presented by the successive methyl transferases. On the other hand, by carrying out similar experiments with brain microsomes fr[Pg.48]

The results of the previous section have shown that the age of the male Wistar rats has a noticeable effect in brain microsomes on the pH value-activity relationship, as regard to lipid methylation. Brain microscmies of 40 days-old rats do not or only slightly possess in fact the pH optimum around 7 found with similar material obtained from the 30 da]rs-old animals (Fig.3 and 4) Parallel experiments carried out in this laboratory on 14 and 20 days-old male %Lstar rats have also indicated variations in pH optima of methylation reactions occurring during maturation. These results would recommend a certain degree of caution in interpreting results of various authors about properties and characteristics of lipid methyl transferases and mi t explain the occurrence in the literature of conflict-... 

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