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Real-Time Observation of Protein Transport across Membranes by Femtosecond Sum Frequency Generation Vibrational Spectroscopy
叶树集
Author NameAffiliationE-mail
叶树集 中国科学技术大学合肥微尺度物质科学国家实验室 shujiye@ustc.edu.cn 
Abstract:
Characterization of kinetic conformational change of proteins at the interfaces is crucial for understanding the biomolecule functions and the mechanism of interfacial biological action. But it requires to capture the dynamic structures of proteins at the interface with sufficient structural and temporal resolutions. Here, we demonstrated that a femtosecond sum frequency generation vibrational spectroscopy(SFG-VS) system developed by our group provides a powerful tool for monitoring the real-time peptide transport across the membranes with time resolution of less than one second. By probing the real-time SFG signals in the amide I and amide A bands as WALP23 interacts with DMPG lipid bilayer, it is found that WALP23 is initially absorbed at the gel-phase DMPG bilayer with a random coil structure. The absorption of WALP23 on the surface leads to the surface charge reversal and thus changes the orientation of membrane-bound water. As the DMPG bilayer changes from gel phase into fluid phase, WALP23 inserts into the fluid-phase bilayer with its N-terminal end moving across the membrane, which causes the membrane dehydration and the transition of WALP23 conformation from random coil to mixed helix/loop structure and then to pure ?-helical structure. The established system is ready to be employed in characterizing other interfacial fast processes, which will be certainly helpful for providing a clear physical picture of the interfacial phenomena.
Key words:  Femtosecond sum frequency generation, peptide transport across membrane, real time, kinetic conformation
FundProject:
Real-Time Observation of Protein Transport across Membranes by Femtosecond Sum Frequency Generation Vibrational Spectroscopy
叶树集
摘要:
Characterization of kinetic conformational change of proteins at the interfaces is crucial for understanding the biomolecule functions and the mechanism of interfacial biological action. But it requires to capture the dynamic structures of proteins at the interface with sufficient structural and temporal resolutions. Here, we demonstrated that a femtosecond sum frequency generation vibrational spectroscopy(SFG-VS) system developed by our group provides a powerful tool for monitoring the real-time peptide transport across the membranes with time resolution of less than one second. By probing the real-time SFG signals in the amide I and amide A bands as WALP23 interacts with DMPG lipid bilayer, it is found that WALP23 is initially absorbed at the gel-phase DMPG bilayer with a random coil structure. The absorption of WALP23 on the surface leads to the surface charge reversal and thus changes the orientation of membrane-bound water. As the DMPG bilayer changes from gel phase into fluid phase, WALP23 inserts into the fluid-phase bilayer with its N-terminal end moving across the membrane, which causes the membrane dehydration and the transition of WALP23 conformation from random coil to mixed helix/loop structure and then to pure ?-helical structure. The established system is ready to be employed in characterizing other interfacial fast processes, which will be certainly helpful for providing a clear physical picture of the interfacial phenomena.
关键词:  Femtosecond sum frequency generation, peptide transport across membrane, real time, kinetic conformation
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