Lipid analyses of isolated surface membranes ofLeishmania Donovani promastigotes

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Abstract
Constituent lipids of surface membranes (SM) isolated fromLeishmania donovani promastigotes were analyzed and compared with those obtained from whole cells and an isolated kinetoplast-mitochondrion fraction (KM). On a dry weight basis, the total extractable lipids constituted ≈47%, 12% and 24% of the SM, cells and KM, respectively. The total lipids of SM, cells and KM all were composed of ≈70% phospholipids (PL), 20–25% neutral lipids and 5–10% glycolipids. Sterols and diglycerides composed 60% and 30%, respectively, of the various neutral lipid fractions. Several mannose- and galactose-containing glycolipids were fractionated but not identified. The glycolipid fractions from cells and SM had demonstrable antigenic activities with rabbit anti-SM sera. Striking quantitative differences were apparent between the PL profiles of the 3 cellular components examined. The PL of SM, whole cells and KM, respectively, were composed of: 15%, 51% and 24% phosphatidylcholine; 37%, 13% and 11% phosphatidylethanolamine (PE); 18%, 10% and 14% phosphatidylinositol; 10%, 1% and 4% phosphatidylserine and traces of cardiolipin, phosphatidylglycerol and phosphatidic acid. An unknown PL containing sphingosine, choline and vicinal hydroxyl groups but no free amino moieties made up ≈19% of the PL of SM and whole cells, but it constituted ≈27% of the PL of KM. The PL side chain constituents of whole cells and SM were composed mainly of longchain fatty acids (C18–20). Further, over 50% of the PE of SM was in the alkyl and alK-1-enyl ether forms. These SM properties might contribute to the organism's resistance to digestion in the hydrolytic environs of both its insect vector and mammalian hosts.

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