A surface equation of state, applicable to liquid-expanded (LE) monolayers, was derived by analyzing the Helmholtz free energy of the LE monolayers. Based on this equation, a general equation was obtained to describe ...A surface equation of state, applicable to liquid-expanded (LE) monolayers, was derived by analyzing the Helmholtz free energy of the LE monolayers. Based on this equation, a general equation was obtained to describe all states of single-component phospholipid monolayers during comprassion. To verify the applicability of the equation, π-A isotherms of 1,2-dipalmitoylphosphatidylcholine (DPPC), 1,2-dipalmitoylphosphatidylglycerol (DPPG), and 1,2-dimyristoyphosphatildylcholine (DMPC) were measured. The comparison between model and experimental values indicates that the equation can describe the behavior of pure phospholipid monolayers.展开更多
The glycosylphosphatidyl inositol(GPI)-anchored proteins are localized on the outer of the plasma membrane and clustered in membrane microdomain known as lipid rafts. Among them, mammalian alkaline phosphatase(AP) is ...The glycosylphosphatidyl inositol(GPI)-anchored proteins are localized on the outer of the plasma membrane and clustered in membrane microdomain known as lipid rafts. Among them, mammalian alkaline phosphatase(AP) is an enzyme widely distributed. So, it has important biological significance to study the combination of AP with lipid monolayer. In our work, the interaction between AP and sphingomyelin has been studied at the air-buffer interface as a biomimetic membrane system by the Langmuir film technique and atomic force microscopy. The surface pressure-area isotherm for the mixed alkaline phosphatase/sphingomyelin monolayer shown the presence of a transition from a liquid-expanded phase to the liquid-expanded/liquidcondensed coexist phase. And the surface compressional modulus suggested the mixed alkaline phosphatase/sphingomyelin monolayer has larger compressibility compared with the pure sphingomyelin monolayer. Besides, according to the micrographs, we inferred when combined with lipid monolayer at the air-buffer interface, the AP molecules formed polymer not multilayer or micelle. And, according to the limiting molecules area of AP, we inferred that 12 AP molecules formed a hexagon polymer unit.展开更多
基金Supported by the National Natural Science Foundation of China (No. 20076012).
文摘A surface equation of state, applicable to liquid-expanded (LE) monolayers, was derived by analyzing the Helmholtz free energy of the LE monolayers. Based on this equation, a general equation was obtained to describe all states of single-component phospholipid monolayers during comprassion. To verify the applicability of the equation, π-A isotherms of 1,2-dipalmitoylphosphatidylcholine (DPPC), 1,2-dipalmitoylphosphatidylglycerol (DPPG), and 1,2-dimyristoyphosphatildylcholine (DMPC) were measured. The comparison between model and experimental values indicates that the equation can describe the behavior of pure phospholipid monolayers.
基金Foundamental Research Funds for the Central Universities(GK201402010)the Natural Science Basic Research Plan in Shaanxi Province of China(2012JQ1002)Innovation Funds of Graduate Programs,SNU(2012CXS033)for supporting this work
文摘The glycosylphosphatidyl inositol(GPI)-anchored proteins are localized on the outer of the plasma membrane and clustered in membrane microdomain known as lipid rafts. Among them, mammalian alkaline phosphatase(AP) is an enzyme widely distributed. So, it has important biological significance to study the combination of AP with lipid monolayer. In our work, the interaction between AP and sphingomyelin has been studied at the air-buffer interface as a biomimetic membrane system by the Langmuir film technique and atomic force microscopy. The surface pressure-area isotherm for the mixed alkaline phosphatase/sphingomyelin monolayer shown the presence of a transition from a liquid-expanded phase to the liquid-expanded/liquidcondensed coexist phase. And the surface compressional modulus suggested the mixed alkaline phosphatase/sphingomyelin monolayer has larger compressibility compared with the pure sphingomyelin monolayer. Besides, according to the micrographs, we inferred when combined with lipid monolayer at the air-buffer interface, the AP molecules formed polymer not multilayer or micelle. And, according to the limiting molecules area of AP, we inferred that 12 AP molecules formed a hexagon polymer unit.
