Alteration of Biomembrane Properties by Trans-Unsaturated Lipids*

Trans-unsaturated lipids have been associated with a higher incidence of heart disease, but not enough is known about the effect of trans-lipids on membrane properties. We use giant unilamellar vesicles (GUVs) as a model membrane system to explore the effect of the trans-lipid, trans-DOPC on biophysical membrane parameters. GUVs are made by electroformation, imaged by confocal microscopy and analyzed for changes in membrane morphology and properties. Trans-DOPC induces some membrane domains to form unusual morphologies that differ from the typical circular and truncated spherical shapes observed in its absence. Trans-DOPC also alters the membrane curvature distribution, especially in the l$_{o}$ phase near the phase boundary where significantly negative curvatures ($<$-0.5 $\mu $m$^{-1})$ are observed. A narrower distribution of meridional curvatures in GUVs with trans-DOPC is suggestive of higher membrane bending rigidity. Though the l$_{o}$-l$_{d}$ area fractions are similar in the presence and absence of trans-DOPC, the ratio of fluorescent intensities in the l$_{d}$/l$_{o}$ phases indicates a greater concentration or brightness of the probes in the l$_{o}$ phase in the presence of trans-DOPC. The presence of trans-lipids could significantly impact cell function.