Infrared Absorption Intensity Analysis as a New Tool for Investigation of Salt Effect on Proteins

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	Infrared Absorption Intensity Analysis as a New Tool for Investigation of Salt Effect on Proteins
	Li, H ; Xu, YY ; Weng, YX
刊名	CHINESE JOURNAL OF CHEMICAL PHYSICS
	2009
卷号	22 期号:6 页码:556
关键词	HELICAL MEMBRANE-PROTEINS ESCHERICHIA-COLI VIBRATIONAL SPECTROSCOPY STABILITY SPECTRA CONFORMATION RHODOPSIN EQUILIBRIUM ULTRAFAST MOLECULES
ISSN号	1674-0068
通讯作者	Weng, YX: Chinese Acad Sci, Inst Phys, Lab Soft Matter Phys, Beijing 100190, Peoples R China.
中文摘要	The native protein structures in buffer solution are maintained by the electrostatic force as well as the hydrophobic force, salt ions play an important role in maintaining the protein native structures, and their effect on the protein stability has attracted tremendous interests. Infrared spectroscopy has been generally used in molecular structure analysis due to its fingerprint resolution for different species including macromolecules as proteins. However spectral intensities have received much less attention than the vibrational frequencies. Here we report that the spectral intensities of protein amide I band, the finger prints for the protein secondary structures, are very sensitive to the local electric field known as Onsager reaction field caused by salt ions. IR absorbance thermal titrations have been conducted for a series of samples including simple water soluble amino acids, water soluble monomeric protein cytochrome c and dimeric protein DsbC and its single-site mutant G49R. We found that at lower temperature range (10-20 degrees C), there exists a thermal activated salting-in process, where the IR intensity increases with a rise in the temperature, corresponding to the ions binding of the hydrophobic surface of protein. This process is absent for the amino acids. When further raising the temperature, the IR intensity decreases, this is interpreted as the thermal activated breaking of the ion-protein surface binding. Applying Van't Hoff plot to the thermal titration curves, the thermodynamic parameters such as Delta H and Delta S for salting-in and ion unbinding processes can be derived for various protein secondary structural components, revealing quantitatively the extent of hydrophobic interaction as well as the strength of the ion-protein binding.
收录类别	SCI
资助信息	National Natural Science Foundation of China [20373088]; Program for Innovation Group [60321002]; Chinese Academy of Sciences [KJCX2-SW-w29]; National Key Project for Basic Research [2006CB910302]
语种	英语
公开日期	2013-09-18
内容类型	期刊论文
源URL	[http://ir.iphy.ac.cn/handle/311004/39944]
专题	物理研究所_物理所公开发表论文_物理所公开发表论文_期刊论文
推荐引用方式 GB/T 7714	Li, H,Xu, YY,Weng, YX. Infrared Absorption Intensity Analysis as a New Tool for Investigation of Salt Effect on Proteins[J]. CHINESE JOURNAL OF CHEMICAL PHYSICS,2009,22(6):556.
APA	Li, H,Xu, YY,&Weng, YX.(2009).Infrared Absorption Intensity Analysis as a New Tool for Investigation of Salt Effect on Proteins.CHINESE JOURNAL OF CHEMICAL PHYSICS,22(6),556.
MLA	Li, H,et al."Infrared Absorption Intensity Analysis as a New Tool for Investigation of Salt Effect on Proteins".CHINESE JOURNAL OF CHEMICAL PHYSICS 22.6(2009):556.