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Alarcon L.M.,CONICET | de los Angeles Frias M.,Laboratorio Of Biointerfases Y Sistemas Biomimeticos | Morini M.A.,CONICET | Belen Sierra M.,CONICET | And 2 more authors.
European Physical Journal E | Year: 2016

Abstract.: We employ molecular dynamics simulations to study the hydration properties of Dipalmitoylphosphatidylcholine (DPPC) bilayers, both in the gel and the liquid crystalline states. We show that while the tight hydration centers (PO and CO moieties) are significantly hydrated in both phases, the gel-fluid transition involves significant changes at the second hydration shell, particularly at the buried region between the hydrocarbon tails. Thus, while almost no buried water population exists in the gel state below the carbonyls, this hydrophobic region becomes partially water accesible in the liquid crystalline state. We shall also show that such water molecules present a lower H-bond coordination as compared to the molecules at the primary hydration shell. This means that, while the latter are arranged in relatively compact nanoclusters (as already proposed), the buried water molecules tend to organize themselves in less compact structures, typically strings or branched strings, with a scarce population of isolated molecules. This behavior is similar to that observed in other hydration contexts, like water penetrating carbon nanotubes or model hydrophobic channels or pores, and reflects the reluctance of water to sacrifice HB coordination. Graphical abstract: [Figure not available: see fulltext.] © 2016, EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.


Cutro A.C.,Laboratorio Of Biointerfases Y Sistemas Biomimeticos | Hollmann A.,Laboratorio Of Biointerfases Y Sistemas Biomimeticos | Cejas J.,Laboratorio Of Biointerfases Y Sistemas Biomimeticos | Maturana P.,Laboratorio Of Biointerfases Y Sistemas Biomimeticos | And 2 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2015

The influence of Phe on the surface pressure of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers at the air-water interface was studied at different initial surface pressures (26 and 40. mN/m) and two pHs (5.0 and 7.3) at constant temperature (20. °C). Changes produced by the aminoacid added to the subphase on the surface pressure and on the dipole potential of lipid monolayers were measured at a fixed area. Compressibility properties of the monolayers at different pHs were studied by (π-A) isotherms. The results suggest that Phe intercalates into a DPPC film at the air-water interface at pH 5 and forms a different arrangement at pH 7.3.The possible relevance of these results of the effect of Phe in physiological conditions is discussed. © 2015 Elsevier B.V.


PubMed | Laboratorio Of Biointerfases Y Sistemas Biomimeticos
Type: | Journal: Colloids and surfaces. B, Biointerfaces | Year: 2015

The influence of Phe on the surface pressure of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) monolayers at the air-water interface was studied at different initial surface pressures (26 and 40 mN/m) and two pHs (5.0 and 7.3) at constant temperature (20 C). Changes produced by the aminoacid added to the subphase on the surface pressure and on the dipole potential of lipid monolayers were measured at a fixed area. Compressibility properties of the monolayers at different pHs were studied by (-A) isotherms. The results suggest that Phe intercalates into a DPPC film at the air-water interface at pH 5 and forms a different arrangement at pH 7.3. The possible relevance of these results of the effect of Phe in physiological conditions is discussed.

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