- Mechanism for remodeling of the acyl chain composition of cardiolipin catalyzed by Saccharomyces cerevisiae tafazzin
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Remodeling of the acyl chains of cardiolipin (CL) is responsible for final molecular composition of mature CL after de novo CL synthesis in mitochondria. Yeast Saccharomyces cerevisiae undergoes tafazzin-mediated CL remodeling, in which tafazzin serves as a transacylase from phospholipids to monolyso-CL (MLCL). In light of the diversity of the acyl compositions of mature CL between different organisms, the mechanism underlying tafazzin-mediated transacylation remains to be elucidated. We investigated the mechanism responsible for transacylation using purified S. cerevisiae tafazzin with liposomes composed of various sets of acyl donors and acceptors. The results revealed that tafazzin efficiently catalyzes transacylation in liposomal membranes with highly ordered lipid bilayer structure. Tafazzin elicited unique acyl chain specificity against phosphatidylcholine (PC) as follows: linoleoyl (18:2) > oleoyl (18:1) = palmitoleoyl (16:1) ? palmitoyl (16:0). In these reactions, tafazzin selectively removed the sn-2 acyl chain of PC and transferred it into the sn-1 and sn-2 positions of MLCL isomers at equivalent rates. We demonstrated for the first time that MLCL and dilyso-CL have inherent abilities to function as an acyl donor to monolyso-PC and acyl acceptor from PC, respectively. Furthermore, a Barth syndrome-associated tafazzin mutant (H77Q) was shown to completely lack the catalytic activity in our assay. It is difficult to reconcile the present results with the so-called thermodynamic remodeling hypothesis, which premises that tafazzin reacylates MLCL by unsaturated acyl chains only in disordered non-bilayer lipid domain. The acyl specificity of tafazzin may be one of the factors that determine the acyl composition of mature CL in S. cerevisiae mitochondria.
- Abe, Masato,Hasegawa, Yui,Oku, Masahide,Sawada, Yoshiki,Tanaka, Eriko,Sakai, Yasuyoshi,Miyoshi, Hideto
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- NMR Studies of Micellar Aggregates in 1-Acyl-sn-glycerophosphocholine Systems. The Formation of a Cubic Liquid Crystalline Phase
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Measurements of the amphiphile diffusion coefficient, using the NMR pulsed-field gradient technique, have been performed on micellar solutions and cubic liquid crystalline phases of the following lysophosphatidylcholines: 1-lauroyl-sn-glycero-3-phosphocholine (LaLPC), 1-myristoyl-sn-glycero-3-phosphocholine (MyLPC), 1-palmitoyl-sn-glycero-3-phosphocholine (PaLPC), 1-stearoyl-sn-glycero-3-phosphocholine (StLPC), 1-oleoyl-sn-glycero-3-phosphocholine (OlLPC), and 1-linoleoyl-sn-glycero-3-phosphocholine (LiLPC).The 2H spin relaxation rates at two magnetic fields have been measured in micellar solutions of PaLPC.The phase equilibria at 25 and 35 deg C in the aqueous binary systems of LaLPC and MyLPC have been studied by 31P NMR and by optical techniques for lipid concentrations up to 50percent (w/w) 2H2O. 2H and 14N quadrupole splittings have been measured in anisotropic phases of PaLPC, OlLPC, and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC).A cubic liquid crystalline phase, I1, located between the micellar and hexagonal phase regions, is formed by LaLPC and MyLPC between approximately 40percent and 45percent (w/w) lipid in 2H2O.As previously shown the I1 phase is also formed by PaLPC while not by StLPC, OlLPC, and LiLPC for which a concentrated micellar solution is in equilibrium with the hexagonal phase (Arvidson et al.Eur.J.Biochem. 1985, 152, 753).For LaLPC, amphiphile diffusion measurements show that the cubic phase I1 consists of closed micellar aggregates.Amphiphile diffusion and 2H spin relaxation studies of the micellar phases show that the aggregates formed by LaLPC, MyLPC, PaLPC, and StLPC remain small and globular over the whole micellar phase region, while the micelles of OlLPC and LiLPC are large and polydispersed.Micelle diffusion measurements provide information about aggregate interactions, which is shown to be compatible with magnitudes of the hydration force and the van der Waals interactions previously obtained for corresponding bilayers.The formation of the cubic face I1 is discussed in terms of the packing of interacting micellar aggregates in a newly proposed structure for the cubic phase.
- Eriksson, Per-Olof,Lindblom, Goeran,Arvidson, Goesta
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- Lytic reactions of drugs with lipid membranes
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Propranolol is shown to undergo lipidation reactions in three types of lipid membrane: (1) synthetic single-component glycerophospholipid liposomes; (2) liposomes formed from complex lipid mixtures extracted from E. coli or liver cells; and (3) in cellulo in Hep G2 cells. Fourteen different lipidated propranolol homologues were identified in extracts from Hep G2 cells cultured in a medium supplemented with propranolol. This isolation of lipidated drug molecules from liver cells demonstrates a new drug reactivity in living systems. Acyl transfer from lipids to the alcoholic group of propranolol was favoured over transfer to the secondary amine. Migration of acyl groups from the alcohol to the amine was diminished. Other drugs that were examined did not form detectable levels of lipidation products, but many of these drugs did affect the lysolipid levels in model membranes. The propensity for a compound to induce lysolipid formation in a model system was found to be a predictor for phospholipidosis activity in cellulo.
- Britt, Hannah M.,García-Herrero, Clara A.,Denny, Paul W.,Mosely, Jackie A.,Sanderson, John M.
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p. 674 - 680
(2019/01/24)
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- Syntheses and antiproliferative activities of novel phosphatidylcholines containing dehydroepiandrosterone moieties
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Dehydroepiandrosterone (DHEA) is a natural hormone with many beneficial properties including an anticancer activity. Unfortunately, DHEA is unstable in the body and exhibits cytotoxicity against healthy cells. In this study, a series of new phosphocholines containing DHEA at sn-1 and/or sn-2 positions were prepared. Succinic acid was used as a linker between the active drug and sn-glycero-3-phosphocholine. All the compounds were evaluated in vitro for their antiproliferative activities against four cell lines: Balb/3T3, HL-60, B16, and LNCaP. The results showed that phosphocholines with DHEA at sn-1 and/or sn-2 positions did not have cytotoxic effects on the normal cell line (Balb/3T3). Mixed-chain phospholipids with DHEA and fatty acid residues showed the highest activity against tumor cell lines. The most active compound, 11c, showed a moderate cytotoxic effect against the HL-60 and B16 cell lines.
- K?obucki, Marek,Grudniewska, Aleksandra,Smuga, Damian A.,Smuga, Ma?gorzata,Jarosz, Joanna,Wietrzyk, Joanna,Maciejewska, Gabriela,Wawrzeńczyk, Czes?aw
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p. 109 - 118
(2017/01/12)
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- Process for preparing lysophoshatidylcholine
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What is described is a process for preparing lysophosphatidylcholine by selective monoacylation of glycerophosphorylcholine (I), in the presence of an acylating agent and of dialkyltin derivatives, according to the following diagram: the process being particularly simple and having high overall yields.
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Page/Page column 7
(2010/11/08)
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- Process for preparing lysophosphatidylcholine
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What is described is a process for preparing lysophosphatidylcholine by selective monoacylation of glycerophosphoryleholine (1), in the presence of an acylating agent and of dialkyltin derivatives, according to the following diagram: the process being particularly simple and having high overall yields.
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Page/Page column 3-4
(2008/06/13)
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- Tin-mediated synthesis of lyso-phospholipids
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1-O-Acyl-sn-glycero-3-phosphocholine and 1-O-acyl-sn-glycero-3-phosphoric acid have been prepared selectively and with high yields from the corresponding diols, glycerophosphoryl choline and glycerol-3-phosphate. Starting from the diols, the activated tin ketals were prepared in 2-propanol by reaction with dialkyltin oxide. The intermediates were acylated in the same solvent with long-chain fatty acid chlorides, giving the corresponding 1-acyl-lyso- phospholipids in high yield and with complete regioselectivity. The catalytic nature of the tin-mediated acylation and the relevance of the solvent are discussed. The Royal Society of Chemistry 2006.
- Fasoli, Ezio,Arnone, Alberto,Caligiuri, Antonio,D'Arrigo, Paola,De Ferra, Lorenzo,Servi, Stefano
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p. 2974 - 2978
(2008/02/11)
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