title: Phase properties of the aqueous dispersions of n-octadecylphosphocholine.
abstract: Properties of the aqueous dispersions of n-octadecylphosphocholine are examined by differential scanning calorimetry, fluorescence depolarization, light scattering, 31P-NMR, pig pancreatic phospholipase A2 binding, and X-ray diffraction. On heating, these dispersions exhibit a sharp lamellar to micelle transition at 20.5 degrees C. The lamellar phase consists of frozen (gel-state) alkyl chains which do not bind phospholipase A2. The kinetics of the transition are asymmetric: the micelle to lamellar transition is very slow and the lamellar to micelle transition is fast. It is suggested that the lamellar phase is a frozen chain bilayer in which the chains interdigitate.
mesh_terms: D000818:Animals; D002152:Calorimetry, Differential Scanning; D005454:Fluorescence Polarization; D008027:Light; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D010179:Pancreas / Q000201:enzymology; D010713:Phosphatidylcholines; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010767:Phosphorylcholine / Q000031:analogs & derivatives*; D012542:Scattering, Radiation; D013552:Swine; D013696:Temperature; D014961:X-Ray Diffraction
chemical_list: D008823:Micelles; D010713:Phosphatidylcholines; D010767:Phosphorylcholine; C032164:n-octadecylphosphocholine; D010741:Phospholipases A; D054467:Phospholipases A2