phenylalanine interaction with membranes in different states of hydration

ANDREA C. CUTRÓ; ANIBAL E. DISALVO

Sierra de la Ventana

Congreso; XLIII Reunión Anual SAB 2014; 2014

sociedad argentina de biofísica

It has been reported that Phenylalanine (Phe) produces leakage and fusion on the thylakoid and liposome membranes during freezing process. Apparently, the damage is related with membranes under stress conditions, i.e. partial dehydration [1]. On the other hand, Phe is able to interact with monolayers of stearic acid producing a disappearance of its liquid-crystalline phase and a premature collapse [2]. Studies carried out in DPPC monolayers (Maturana et al, SAB 2014) showed that the Phe-lipid interaction depends on the water content. In order to correlate the Phe interaction with the hydration state in bilayers we study the interaction of Phe in DPPC liposomes in gel (25°C) and liquid-crystalline phases (50°C) and in liposomes in the gel state subjected to osmotic dehydration. The effect was measured using Merocyanine (MC 540) as a fluorescent marker. The presence of Phe in DPPC liposomes at 50°C, does not produce significant change in MC 540 monomer concentration. On the contrary, in DPPC liposomes at 25°C Phe decreases significantly the monomer adsorption. This behavior was also observed, when DPPC liposomes were subjected to a hypertonic media. These results indicate that phenylalanine interaction depends on the membrane hydration states. References [1] Popova, A. V. et al. Biochimica et Biophysica Acta (2002), 109.  [2] Griffith, E. C et al. The Journal of Physical Chemistry (2012), 7849.