Interaction of Phenylalamine With Lipid Membranes: More Than a Hydrophobic Interaction

ROSA, A.S ; CUTRO, A.C.; FRÍAS, M.A.; DISALVO, E.A.

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Lugar: Washington; Año: 2015

1520-6106

The negative free energy previously reported is explained by the stabilization of a PC-Phe complex in the presence of water shown by the decrease in the PO in the presence of water. An entropic contribution due to the disruption of the water network around the phenyl and in the membrane defect may be invoked. The insertion would promote spacing of the PO groups that are facing to water in the surface as shown by the frequency decrease. The dipole potential decrease is explained by the orientation of the carboxylate opposing to the CO of the lipids with oxygen moiety towards 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 = 2.22 ± 0.08 mM, from which the free energy change is about -4. 54 kcal/mol at 25oC. This may be due to hydrophobic contributions and two hydrogen bonds.