1,6-Diphenyl-1,3,5-hexatriene (DPH) is one of the most commonly used fluorescent probes to study dynamical and structural properties of lipid bilayers and cellular membranes via measuring steady-state or time-resolved fluorescence anisotropy. In this study, we present a limitation in the use of DPH to predict the order of lipid acyl chains when the lipid bilayer is doped with itraconazole (ITZ), an antifungal drug. Our steady-state fluorescence anisotropy measurements showed a significant decrease in fluorescence anisotropy of DPH embedded in the ITZ-containing membrane, suggesting a substantial increase in membrane fluidity, which indirectly indicates a decrease in the order of the hydrocarbon chains. This result or its interpretation is in disagreement with the fluorescence recovery after photobleaching measurements and molecular dynamics (MD) simulation data. The results of these experiments and calculations indicate an increase in the hydrocarbon chain order. The MD simulations of the bilayer containing both ITZ and DPH provide explanations for these observations. Apparently, in the presence of the drug, the DPH molecules are pushed deeper into the hydrophobic membrane core below the lipid double bonds, and the probe predominately adopts the orientation of the ITZ molecules that is parallel to the membrane surface, instead of orienting parallel to the lipid acyl chains. For this reason, DPH anisotropy provides information related to the less ordered central region of the membrane rather than reporting the properties of the upper segments of the lipid acyl chains.

Department of Physics Tampere University of Technology PO Box 692 FI 33101 Tampere Finland

Department of Physics Tampere University of Technology PO Box 692 FI 33101 Tampere Finland; Department of Physics University of Helsinki PO Box 64 FI 00014 Helsinki Finland

Faculty of Chemistry Jagiellonian University Gronostajowa 2 30 387 Kraków Poland

J Heyrovský Institute of Physical Chemistry AS CR v v i Dolejškova 2155 3 182 23 Prague 8 Czech Republic

Max Planck Institute of Colloids and Interfaces Science Park Golm 14424 Potsdam Germany

Citace poskytuje Crossref.org

Repurposing of MitoTam: Novel Anti-Cancer Drug Candidate Exhibits Potent Activity against Major Protozoan and Fungal Pathogens

The Two Faces of the Liquid Ordered Phase