Physical properties of the hybrid lipid POPC on micrometer-sized domains in mixed lipid membranes

Phys Chem Chem Phys. 2015 Aug 28;17(32):20882-8. doi: 10.1039/c5cp03377b. Epub 2015 Jul 27.

Abstract

Macro-phase separation in mixed lipid membranes containing the hybrid lipid palmitoyloleoylphosphatidylcholine (POPC) was observed by fluorescent and confocal laser scanning microscopy. In a binary system consisting of the saturated lipid dipalmitoylphosphatidylcholine (DPPC) and the hybrid lipid POPC, the hybrid lipid forms a liquid-disordered (Ld) phase. In a ternary system consisting of this binary system and an unsaturated lipid dioleoylphosphatidylcholine (DOPC), three-phase coexistence is observed. The POPC-rich phase appears around DPPC-rich domains, and the hybrid lipid is expected to behave like a line-active agent (linactant). Finally, phase separation in a four-component system, composed of this ternary system and cholesterol, was examined. Domains with a size that is smaller than 1 μm are found, and domain-induced budding is also observed. To explain small domain formation and domain-induced budding, chain ordering was evaluated based on Laurdan generalized polarization measurements. Our observations revealed that the hybrid lipid acted like a linactant to solid domains and disturbed chain ordering in liquid-ordered (Lo) domains. In both cases, the hybrid lipid reduced line tension at the domain boundary.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chemistry, Physical
  • Microscopy, Confocal
  • Microscopy, Fluorescence
  • Particle Size
  • Phosphatidylcholines / chemistry*
  • Surface Properties

Substances

  • Phosphatidylcholines
  • 1,2-oleoylphosphatidylcholine
  • 1-palmitoyl-2-oleoylphosphatidylcholine