title: Components and fractions for differently bound water molecules of dipalmitoylphosphatidylcholine-water system as studied by DSC and 2H-NMR spectroscopy.
abstract: Differently bound water molecules of dipalmitoylphosphatidylcholine (DPPC)-H2O system were investigated with differential scanning calorimetry (DSC). According to a method previously reported by us, the ice-melting DSC curves of the DPPC-H2O samples of varying water contents were deconvoluted into multiple components, and the ice-melting enthalpies for the individual deconvoluted components were used to estimate average molar ice-melting enthalpies for freezable interlamellar and bulk waters, respectively. With these average molar ice-melting enthalpies, the numbers of differently bound water molecules of the DPPC-H2O system were calculated at varying water contents and were used to construct a water distribution diagram of this system. Furthermore, to evaluate the reliability of the present DSC deconvolution method, 2H-NMR T1 measurements of DPPC-2H2O system were carried out at 5 degrees C of the gel phase temperature, and components and fractions for differently bound water (2H2O) molecules were estimated from the analysis of nonexponential magnetization recovery curves.
authors.affiliation: Department of Biochemistry, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan. kodama@dbc.ous.ac.jp
authors.forename: M
authors.initials: M
authors.lastname: Kodama
authors.forename: Y
authors.initials: Y
authors.lastname: Kawasaki
authors.forename: H
authors.initials: H
authors.lastname: Aoki
authors.forename: Y
authors.initials: Y
authors.lastname: Furukawa
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D003903:Deuterium; D008051:Lipid Bilayers / Q000737:chemistry*; D019906:Nuclear Magnetic Resonance, Biomolecular; D044367:Phase Transition; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D008051:Lipid Bilayers; D014867:Water; D015060:1,2-Dipalmitoylphosphatidylcholine; D003903:Deuterium