Details

Autor(en) / Beteiligte

• Singh, Alok
• Burke, Thomas G.
• Calvert, Jeffrey M.
• Georger, Jacque H.
• Herendeen, Barbara
• Price, Ronald R.
• Schoen, Paul E.
• Yager, Paul

Titel

Lateral phase separation based on chirality in a polymerizable lipid and its influence on formation of tubular microstructures

Ist Teil von

• Chemistry and physics of lipids, 1988-06, Vol.47 (2), p.135-148

Ort / Verlag

Shannon: Elsevier Ireland Ltd

Erscheinungsjahr

1988

Quelle

Elsevier Journal Backfiles on ScienceDirect (DFG Nationallizenzen)

Beschreibungen/Notizen

• No difference is believed to exist between the physical properties of racemic and enantiomeric phospholipids. We report here the first observation of lateral phase separation of phospholipids on the basis of the chirality of the glycerol backbone. The chiral polymerizable diacetylenic lecithin 1,2-bis-(10,12-tricosadiynoyl)- sn-glycero-3-phosphocholine, or l-DC 8,9PC, spontaneously forms hollow cylindrical structures, or tubules, and similar right-handed helices. To determine the influence of chirality of the lipid on the morphology of the resultant microstructures, d-DC 8,9 and rac-DC 8,9PC were synthesized. The T vs. X L phase diagram for the lipids in excess water indicates formation of a racemic mixture, with no appreciable co-crystallization of the enantiomers in the bilayer plane. When exposed to tubule-forming conditions, rac-DC 8,9PC produced tubules, right- and left-handed helices, and a small proportion of anomalous microstructures such as flat and loosely-wound sheets, and pairs of tubules linked by sheets. The formation of chiral structures is consistent with the thermodynamic data, suggesting that lateral phase separation on the basis of chirality is responsible for formation of tubules from rac-DC 8,9PC liposomes, and that when monomer is precipitated from alcoholic solution the resultant microstructures are of predominantly one handedness or the other. The unusually poor miscibility of the enantiomers is the low temperature phase can be explained by hydrocarbon chain packing constraints imposed by the diacetylene moiety.