title: Pressure jump relaxation investigations of lipid membranes using FTIR spectroscopy.
abstract: The relaxation kinetics of aqueous lipid dispersions after a pressure jump (p-jump) were investigated using time-resolved FTIR spectroscopy. The methylene stretching vibrational band and the carbonyl band were analyzed to detect changes in conformational order of the hydrocarbon chains and to follow the degree of hydration of the head group, respectively. The kinetics of the transition was found to consist of multiple processes with relaxation constants from seconds down to milliseconds. Faster processes are also present, but could not be resolved by our instrument. This is the first investigation showing directly the time resolved change in chain order in lipid bilayers induced by a p-jump. The results obtained with this IR detection method support previous results that the change in chain order after a perturbation is a multi-step process with the initial molecular events occurring with time constants shorter than milliseconds.
authors.affiliation: Faculty of Chemistry and Physics, Institute of Chemistry, Martin-Luther-University Halle-Wittenberg, Mühlpforte 1, 06108 Halle (Saale), Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schiewek
authors.forename: Alfred
authors.initials: A
authors.lastname: Blume
mesh_terms: D004735:Energy Transfer; D007700:Kinetics; D008697:Methane / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D008968:Molecular Conformation; D044367:Phase Transition; D010743:Phospholipids / Q000032:analysis / Q000737:chemistry*; D011312:Pressure; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D013816:Thermodynamics; D014732:Vibration; D014867:Water / Q000737:chemistry
chemical_list: D010743:Phospholipids; C504223:methylene radical; D014867:Water; D008697:Methane