Headgroup Mobility in the Low Temperature Phase (Lσ′) of DPPC

摘要: Abstract The 1H decoupled Phosphorus NMR lineshape of DPPC-water dispersions shows characteristic changes when passing through the three thermotropic phase transitions: subtransition (Lσ′ - Lβ′), pretransition (Lβ′ Pβ′) and main transition (Pβ -Lα). At spectrum from a non-axial-symmetric powder (Lσ′) to an axial-symmetric one (Lβ′). two higher transitions are characterized by decreases in intrinsic 31P line widths chemical shift anisotropy. Proton-enhanced 13C-spectra same compound, with natural isotope abundance, recorded at 76 MHz permit resolved observation different carbon-positions headgroup. In particular N-(CH3)3-carbon nuclei exhibit narrow isotropic throughout entire observed temperature range (-20°C … 50°C). This implies that rotational motion this moiety does not cease below subtransition. To summarize, headgroup mobility Lσ'-phase can be described as follows: rotation o...