Kinetics for the subgel phase formation in DPPC/DOPC mixed bilayers.
We analyzed the kinetics for the subgel (SGI) phase formation in DPPC/DOPC binary bilayers paying attention to DOPC-induced modification of the bilayer physical properties. Differential scanning calorimetry and X-ray diffraction revealed that addition of DOPC reduced the apparent initial lag time to start the SGI phase formation, and that the SGI phase in the binary bilayers had basically the same structure as that in pure DPPC bilayers though addition of DOPC markedly increased the peak temperature and enthalpy of the subtransition in heating. Moreover, addition of DOPC abolished the prolongation of the initial lag time in pure DPPC bilayers induced by lowering the incubation temperature from 0 to -5 degrees C. Our results suggested that DOPC molecules work as a diffusion enhancer to promote the nucleation of the SGI phase, and relatively destabilize the gel phase so that the formed SGI phase transforms into the ripple phase in heating.
Kinoshita
Masanao
M
Department of Physics, School of Science and Technology, Kwansei-Gakuin University, 2-1 Gakuen, Sanda, Hyogo 669-1337, Japan. aul81636@kwansei.ac.jp
Ito
Keisuke
K
Kato
Satoru
S
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D005782:Gels / Q000737:chemistry*; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry*; D009995:Osmosis; D044367:Phase Transition; D010713:Phosphatidylcholines / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014961:X-Ray Diffraction
D005782:Gels; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D015060:1,2-Dipalmitoylphosphatidylcholine; C017251:1,2-oleoylphosphatidylcholine