Browsing by Author "Moraes, G"

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    Stereoselective synthesis of perdeuterated phytanic acid, its phospholipid derivatives and their formation into lipid model membranes for neutron reflectivity studies
    (Elsevier, 2014-10-01) Yepuri, NR; Holt, SA; Moraes, G; Holden, PJ; Hossain, KR; Valenzuela, SM; Darwish, TA; James, M
    We describe a straightforward method, for synthesis of large scale (gram quantities) of highly deuterated phytanic acid from commercially available phytol while preserving the stereochemistry around the chiral centres. The subsequent synthesis of tail-deuterated analogues of the archeabacterial membrane lipids 1,2-di(3RS,7R,11R-phytanyl)-sn-glycero-3-phosphocholine (DPEPC) and 1,2-di(3RS,7R,11R-phytanoyl)-sn-glycero-3-phosphocholine (DPhyPC) from perdeuterated phytanic acid is also described. Both lipids were employed in construction of two different model membranes, namely Langmuir monolayers and a tethered bilayer membrane (TBM) on a solid substrate, characterised by pressure area isotherm and neutron reflectometry techniques. At 10 mN/m pressure the head-group thickness of both monolayers was similar while the thickness of the tail region was significantly larger for tail-deuterated DPhyPC, which was evident from a smaller area per molecule. At 20 mN/m the thickness of the head and tail regions in both lipids was comparable, yet the area per molecule of tail-deuterated DPhyPC was 10% smaller than tail-deuterated DPEPC. In the TBM bilayer model membrane, the thickness of the lipid tails in both inner and outer leaflets was 8.2 Å, giving a total of 16.4 Å. Deuteration enabled unambiguous determination of the relative proportion of the hydrogenous tether, phospholipid and subphase. © 2014, Elsevier Ireland Ltd.
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    Synthesis of deuterated [D-32]oleic acid and its phospholipid derivative [D-64]dioleoyl-sn-glycero-3-phosphocholine
    (Wiley-Blackwell, 2013-07-16) Darwish, TA; Luks, E; Moraes, G; Yepuri, NR; Holden, PJ; James, M
    Oleic acid and its phospholipid derivatives are fundamental to the structure and function of cellular membranes. As a result, there has been increasing interest in the availability of their deuterated forms for many nuclear magnetic resonance, infrared, mass spectroscopy and neutron scattering studies. Here, we present for the first time a straightforward, large-scale (gram quantities) synthesis of highly deuterated [D32]oleic acid by using multiple, yet simple and high yielding reactions. The precursors for the synthesis of [D32]oleic acid are [D14]azelaic acid and [D17]nonanoic acid, which were obtained by complete deuteration (>98% D) of their 1H forms by using metal catalysed hydrothermal H/D exchange reactions. The oleic acid was produced with ca. 94% D isotopic purity and with no contamination by the trans-isomer (elaidic acid). The subsequent synthesis of [D64]dioleoyl-sn-glycero-3-phosphocholine from [D32]oleic acid is also described. Copyright © 2013 John Wiley & Sons, Ltd.© 2013, Wiley-Blackwell.