Mixed alkaline phosphatase/sphingomyelin monolayer at the air-buffer interface: phase behavior and morphology  

作　　者：WANG Juan SUN RunGuang HAO ChangChun 

机构地区：[1]Laboratory of Biophysics and Biomedicine, College of Physics and Information Technology, Shaanxi Normal University

出　　处：《Science China Chemistry》2014年第11期1538-1543,共6页中国科学（化学英文版）

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

摘　　要：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.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.

关 键 词：alkaline phosphatase Langmuir monolayers GPI-anchored protein atomic force microscopy biomimetic systems 

分 类 号：O621.13[理学—有机化学]