Interaction of L-arginine with dihexadecylphosphate unilamellar liposomes: the effect of the lipid phase organization.
The interaction of L-arginine with unilamellar liposomes of dihexadecylphosphate sodium salt (DHP-Na) has been investigated using calorimetric, light scattering, fluorescence spectroscopy and zeta-potential techniques. Heating from room temperature, the bilayer exhibits a phase transition from a subgel (L(c)) to the gel (L(beta')) phase as well as a pre-transition (L(beta')-P(beta')), which is followed by the main lipid phase transition (P(beta')-L(alpha)). Direct studies of the interaction of L-arginine with the DHP-Na bilayers via isothermal titration calorimetry at 27 degrees C depict significant differences between samples in the L(c) and the L(beta') phases reflecting the effect of molecular organization of the lipids upon the interaction. While L-arginine has only a small impact upon the L(c) to L(beta') phase transition, it affects more significantly the transition temperature as well as the shape of the DSC peaks of the main lipid phase transition. Based on fluorescence and zeta-potential studies, the permeability of L-arginine through the liposomal membrane is higher within the temperature range of the main lipid phase transition. Encapsulated l-arginine obstructs the formation of the subgel phase.
Tsogas
Ioannis
I
Institute of Physical Chemistry, NCSR Demokritos, 153 10 Aghia Paraskevi, Greece.
Tsiourvas
Dimitris
D
Paleos
Constantinos M
CM
Giatrellis
Sarantis
S
Nounesis
George
G
D001120:Arginine / Q000737:chemistry*; D002151:Calorimetry / Q000379:methods; D008027:Light; D008081:Liposomes; D010755:Organophosphates / Q000737:chemistry*; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence
D008081:Liposomes; D010755:Organophosphates; C002290:dicetylphosphate; D001120:Arginine