The unsaturated fatty acids contained in single-cell proteins prepared from Li 70 yeasts grown on methanol were studied in order to ascertain the position of unsaturation and the stereochemistry of the double bonds. The acids were extracted and esterified to the corresponding fatty acid methyl esters (FAMEs) as described in previous reports. The location of the double bonds was obtained by gas-chromatographicmass-spectrometric analysis of the trimethylsilyloxy derivatives of the FAMEs. The stereochemistry was deduced by nuclear magnetic resonance spectroscopy using an incremental addition study with Eu(fod), on FAMEs and on the corresponding epoxy derivatives. Three model FAME samples, methyl oleate (~c-C,,:,), methyl elaidate (9t-C18:,) and methyl linoleate (gc, 1 2 ~-C ~~: ~) , were compared. Most of the unsaturated fatty acids (about 74%) present in the single-cell proteins have structures identical with those known in animal lipids. The three most abundant unsaturated fatty acids display the following structure : ~C -C ~~: ~ (22.5y0), 9c-Cl8:, (19.4%) and 9 ~, 1 2 c -C , ~: ~ (29.2%). All double bonds possess a cis-configuration; the position of the double bond is a t C9-C10 for the monounsaturated acids and C9-C10 and C12-Cl3 for diunsaturated acids.
1he nuclear magnetic resonance spectroscopic analysis of the reaction mixtures obtained in the catalytic oxidation of m-diisopropylbenzene is reported. The solvent effects on the methyl resonances due to -C(CH,),OO-, -C(CH,),OOH, -C(CH,),OH and -CH(CH,), groups in the oxidation products have been studied, using as reference compounds the main reaction products, which had been synthesised for this purpose. The best results for the resolutions of the different resonances and their assignments were obtained by using deuteroacetone-d, as solvent. The quantitative evaluation of the various components present in the crude reaction mixtures is shown to be possible.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.