Lyotropic model membrane structures of hydrated DPPC: DSC and small-angle X-ray scattering studies of phase transitions in the presence of membranotropic agents |
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| Authors: | LA Bulavin DV Soloviov VI Gordeliy OS Svechnikova AO Krasnikova NA Kasian |
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| Institution: | 1. Taras Shevchenko National University of Kyiv, Kyiv, Ukraine;2. Institute for Safety Problems NPP, NAS of Ukraine, Kyiv, Ukraine;3. Joint Institute of Nuclear Research, Dubna, Russia;4. Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, Dolgoprudniy, Russia;5. ICS-5, Forschungszentrum Jülich, Jülich, Germany;6. Institute of Structural Biology J.P.Ebel, Grenoble, France;7. Institute for Scintillation Materials of STC ‘Institute for Single Crystals’, NAS of Ukraine, Kharkov, Ukraine |
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| Abstract: | Multibilayer structures of hydrated phospholipids, often considered as model biological membranes, are, from the physical viewpoint, lyotropic liquid crystalline systems undergoing temperature-induced mesomorphic phase transitions. Effects of silver nitrate and urocanic acid on lyotropic phase states of hydrated L-α-dipalmitoylphosphatidylcholine (DPPC) have been studied by small-angle X-ray scattering and differential scanning calorimetry (DSC). Both methods show increase of the main phase-transition temperature (Tm) of hydrated DPPC upon introduction of AgNO3 or urocanic acid, decrease of pre-transition temperature (Tp) in the presence of urocanic acid and its increase in the presence of AgNO3. Thus, urocanic acid widened the ripple-phase temperature region. Silver nitrate caused the appearance of an additional high-temperature peak on DSC thermograms, evidencing phase separation in the system. Both agents caused minor effects on DPPC lipid bilayer repeat distance (D) in gel phase, but resulted in noticeable increase of D in the liquid crystal phase with temperature as compared to undoped DPPC structures. |
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| Keywords: | lyotropic liquid crystal hydrated DPPC urocanic acid silver nitrate small-angle X-ray scattering differential scanning calorimetry phase transitions drug–membrane interaction |
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