Monitoring the pH Triggered Collapse of Liposomes in the Far IR Hydrogen Bonding Continuum.
Far infrared spectra of complex molecular structures like lipid membranes or proteins show large and broad continuum modes that include contributions of the internal hydrogen bonding of the assembled structures. Here we corroborate the pH triggered structural rearrangement in pH-sensitive liposomes with a clear shift of the far-infrared mode from 170 to 159 cm(-1). This spectral change was accompanied by the broadening of the hydrogen bonding signature by about 25 cm(-1) and correlates with the well-known hydrogen bonding dependent shifts of the ν(PO2(-))(as) vibration of the lipid headgroup in the mid infrared and with further shifts of functional group vibrations. Far infrared spectroscopy is thus a useful tool for the investigation of conformational changes in large molecular structures.
Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Université de Strasbourg-CNRS , 1 Rue Blaise Pascal, Strasbourg 67070, France.
Batoul
B
Srour
Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology and Biopharmacy and Freiburger Materialforschungszentrum (FMF), Albert Ludwig University Freiburg , Freiburg, Germany.
Birgit
B
Erhard
Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology and Biopharmacy and Freiburger Materialforschungszentrum (FMF), Albert Ludwig University Freiburg , Freiburg, Germany.
Regine
R
Süss
Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, Université de Strasbourg-CNRS , 1 Rue Blaise Pascal, Strasbourg 67070, France.
Petra
P
Hellwig
D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000737:chemistry*; D015394:Molecular Structure; D013055:Spectrophotometry, Infrared
D008081:Liposomes