Determination of the complete structure of natural lecithins

Abstract

A method is described for the separation, identification, and quantitative estimation of the individual molecular species occurring in natural lecithin mixtures. Purified lecithin preparations are converted into diglyceride acetates by enzymic dephosphorylation and acetylation. The diglyceride acetates are separated on the basis of the degree of unsaturation and the molecular geometry by means of chromatography on thin layers of silica gel which are impregnated with silver nitrate. The various acetates thus resolved are separately recovered from the plates and diluted with tridecanoin internal standard; the quantitative distribution of the molecular weights is determined by gas chromatography.Suitable aliquots of the saturated and unsaturated diglyceride acetates are further analyzed for over-all and for positional distribution of fatty acids. The identity and proportions of the various lecithins are deduced by integration and normalization of all the experimental data. Where doubt exists, specific diglyceride acetates are isolated by preparative gas chromatography, and their fatty acid composition is determined. The method is illustrated with data obtained for the mixed lecithins of egg yolk. The general approach is applicable to the determination of the structure of other phospholipids of comparable complexity.

AAV8-Mediated Long-Term Expression of Human LCAT Significantly Improves Lipid Profiles in hCETP;Ldlr+/− Mice

“…This observation is consistent with the fact that human LCAT favors 18:2 and 18:1 more than 20:4 and 22:6 at the sn-2 position, whereas mouse LCAT is the opposite [32,33]. No other deuterium-labeled CE species were detected, consistent with the fact that 18:2, 18:1, 20:4, and 22:6 constitute the majority of fatty acyl groups in the sn-2 position of egg yolk PC in the substrate [34,35]. In conclusion, circulating hLCAT in these hCETP;Ldlr +/− mice was functionally active, and its substrate specificity was characteristic of the human enzyme.…”

Biochemical characterization of pulmonary washings of patients with alveolar proteinosis, interstitial pneumonitis and alveolar cell carcinoma.

“…In order to determine the detailed molecular species of the disaturated classes, the carbon number distribution of the diacylglycerol acetates separated on the basis of the degree of unsaturation was analyzed by gas chromatography (Kuksis and Marai 1967). The diacylglycerol acetates were analyzed on a 50 cm x 4 mm (outer diameter) pyrex column packed with 1% silicone OV-1 on Gaschrom Q at 290°C.…”

A convenient method for lecithin purification from fresh eggs

“…16 The number of carbons of the fatty acid chains range from 14 to 22 and 0 to 6 double bonds can be present in each fatty acid. 17,18 Fractions 13 -15 were analyzed by ESI Mass spectra, in the positive mode, where the molecular mass of the lecithin analogs can be determined (Figure 2). …”