N-butanol partitioning and phase behavior in DPPC/DOPC membranes

Document Type


Date of Original Version



Membrane phase behavior and fluidization have been examined in heterogeneous membranes composed of dipalmitoylphosphatidylcholine (DPPC, a saturated lipid) and dioleoylphosphatidylcholine (DOPC, an unsaturated lipid) at nbutanol concentrations below and above the interdigitation threshold of DPPC. Our results show that the presence of DOPC did not influence the interdigitation concentration of n-butanol on DPPC (0.1-0.13 M) despite the fact that DOPC increased nbutanol partitioning into the membranes. When DPPC was the continuous phase, up to equimolar DPPC:DOPC, n-butanol partitioning into gel or interdigitated DPPC was only slightly affected by the presence of DOPC. In this case a "cooperative effect" of DOPC + n-butanol eliminated the DPPC pretransition phase and yielded an untilted gel-like phase. When DOPC was the continuous phase, more n-butanol was needed to cause DPPC interdigitation (0.2 M), which was attributed to n-butanol residing at the interface between DOPC and DPPC domains. To our knowledge, this is the first study to examine the effects of nbutanol partitioning on membranes composed of saturated and unsaturated lipids that exhibit coexisting phase states. © 2012 American Chemical Society.

Publication Title, e.g., Journal

Journal of Physical Chemistry B