Thermodynamic Chracterisation Of The Lipid Monolayer And The Combination Of The Proteins And Lipid At Air-water Interface

Biomembrane is a supermolecule system consisted of lipid、protein and saccharide, which is significant in many vital processes,such as the energy transformation of cells、substance transportation、signal identificaton and transduction. Thus, the investigation of biomembrane characheristic is of great significance in biology, also, can provide with information for the preparation of target drug and clinicalcare. Langmuir film is one of the most efficiency models used to investigate the membranes.In this paper, we have researched raft proteins and lipids interactions in two respects:(1) Thermodynamic Study on the mixed Monolayer:Different Choi-content and PE/PC(2:1,1:1,1:2) formed a supermolecule system, the compressibility and stability of which were analysed from the perspective of physical chemistry and the surface of which was observed by atomic force microscopy. It has been researched that the effect different Choi-content on PE/PC mixed monolayers and the interaction between the lipid molecules.(2)Interaction between the proteins and lipid monolayers:Mammalian alkaline phosphatases are widely distributed enzymes on the outer of the plasma membrane. In this work, the interaction between alkaline phosphatases and sphingomylin monolayers.Using the ionic strength to induce alkaline phosphatase on the interface, the mixed alkaline phosphatase/sphingomylin monolayers were studied onto air-buffer surface. From the surface pressure-area per molecule isotherms, the surface pressure-time curves and the surface compressional modulus of pure sphingomylin or mixed monolayers, we have obtained some results. The stransition from a liquid-expanded phase to the liquid-expanded/liquid-condensed coexist phase exists on the isotherm for the mixed monolayers. And the addition of proteins has little influence to the stability of the monolayer. It has been shown that more than10of alkaline phosphatase molecules were clustered as a unit and than combined with sphingomylin to form the monolayer, according to the limiting molecular area and the height analysis.