The Molecular Structure And Dynamics At The Interface Of Biological Membrane Investigated By Chiral And Achiral Sum Frequency Generation Vibrational Spectroscopy

To maintain the normal life activities,only the specific chiral molecules realize the specific function.Studying the chiral biological molecules of biological membrane interface is very important to understand the pathogenesis of some disease.Understanding chiral biological molecules of biological membrane interface not only contribute to find the pathogenesis but also provide guidance to the research of new drugs.However it is complex for studying chiral biological molecular on biological membrane interface,the main reason is lacking in valid,real time,in situ and label-free method.To solve this problem,this dissertation applied interface-sensitive sum frequency generation vibrational spectroscopy(SFG-VS)combining achiral and chiral polarization measurements,studying the transport and organization of cholesterol on biological membrane interface and the secondary structure transformation of hIAPP protein.We chose two molecules,cholesterol and hMAPP protein as the models.We systematically investigate the transport and organization of cholesterol in neutral PC phospholipid bilayer and negative phospholipid/(DMPC+d-cholesterol)bilayer.It is found that cholesterol molecular in neutral PC phospholipid flip-flop quickly while it has opposite result in negative phospholipid/(DMPC+d-cholesterol)bilayer.All the data proved that the transport and organization of cholesterol in planar solid-supported lipid bilayer depend on the phospholipid flip-flop rate.The conclusion was further proved by adding the salt solutions.We also applied this method to detect the secondary structure of hIAPP protein in different phospholipid bilayer,and the effect of inhibitor on hIAPP protein.It found that hIAPP protein would be aggregated on the surface of biological membrane,and the degree of aggregation has a great correlation with the presence of amide ?.