Reorganization of Hydration Water of DPPC Multilamellar Vesicles Induced by L-Cysteine Interaction

JUAN M. ARIAS; M. E. TUTTOLOMONDO; SONIA B. DÍAZ; AIDA BEN ALTABEF

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Año: 2018 vol. 122 p. 5193 - 5204

1520-6106

The aim of this study is to analyze theconsequences of water redistribution on the structure andstability of phospholipid bilayers induced by cysteine (Cys).This interaction is studied with 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) multilamellar vesicles in gel (30°C) and liquid crystalline (50 °C) state; experimental studieswere performed by means of Fourier transform infrared(FTIR) spectroscopy, Raman spectroscopy, and differentialscanning calorimetry (DSC). The polar head sites of the lipidmolecules to which water can bind are identified bycompetition with compounds that form hydrogen bonds,such as Cys. FTIR spectroscopy results revealed that there is aCys interaction with the phospholipid head groups in the geland liquid crystalline phases. Raman spectra were measured in the gel state. They were dominated by vibrations of the fatty acylchains, with superposition of a few bands from the head group, and clearly showed that the S−H stretching band of Cys shiftedto lower frequencies with a decrease in its force constant. DSC disclosed an overview of the behavior of the multilamellar vesiclesin the working temperature range (30−50 °C) and showed how the increase of the molar ratios modified the environment of thepolar head and the hydrocarbon chains. A loss of the pretransition (TP) and an increase in the temperature of main transition(Tm) with increasing Cys/DPPC molar ratio were observed.