title: Interaction of Phenylalanine with DPPC Model Membranes: More Than a Hydrophobic Interaction.
abstract: The negative free energy previously reported is explained by the stabilization of a PC-Phe (phosphocholine-phenylalanine) complex in the presence of water shown by the decrease in the symmetric stretching frequency of the phosphate group of the lipid (PO2(-)). An entropic contribution due to the disruption of the water network around the phenyl and in the membrane defect may be invoked. The dipole potential decrease is explained by the orientation of the carboxylate opposing to the CO of the lipids with oxygen moiety toward the low hydrated hydrocarbon core. The symmetric bending frequency of NH3(+) group of Phe, decreases in 5.2 cm(-1) in relation to water congruent with zeta potential shift to positive values. The Phe to DPPC dissociation constant is Kd = 2.23 ± 0.09 mM, from which the free energy change is about -4.54 kcal/mol at 25 °C. This may be due to hydrophobic contributions and two hydrogen bonds.
authors.affiliation: Laboratory of Biointerphases and Biomimetic Systems, CITSE (University of Santiago del Estero- CONICET) , 4200 Santiago del Estero, Argentina.|Universidad de Santiago del Estero-Facultad de Agronomía y Agroindustria , Santiago del Estero Province Argentina.
authors.forename: A S
authors.initials: AS
authors.lastname: Rosa
authors.affiliation: Laboratory of Biointerphases and Biomimetic Systems, CITSE (University of Santiago del Estero- CONICET) , 4200 Santiago del Estero, Argentina.
authors.forename: A C
authors.initials: AC
authors.lastname: Cutro
authors.affiliation: Laboratory of Biointerphases and Biomimetic Systems, CITSE (University of Santiago del Estero- CONICET) , 4200 Santiago del Estero, Argentina.
authors.forename: M A
authors.initials: MA
authors.lastname: Frías
authors.affiliation: Laboratory of Biointerphases and Biomimetic Systems, CITSE (University of Santiago del Estero- CONICET) , 4200 Santiago del Estero, Argentina.|Universidad de Santiago del Estero-Facultad de Agronomía y Agroindustria , Santiago del Estero Province Argentina.
authors.forename: E A
authors.initials: EA
authors.lastname: Disalvo
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000031:analogs & derivatives* / Q000737:chemistry; D019277:Entropy; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D010649:Phenylalanine / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; C081581:colfosceril palmitate; D010649:Phenylalanine