Biophysical studies of the interaction between a triazole derivative and bovine serum albumin by multi-spectroscopic and molecular modeling methods  

作　　者：FU JiaXin WANG KaiWei GE YuShu JIANG FengLei SUN XiaoHong LIU Yang LIU Yi 

机构地区：[1]Department of Chemical Engineering,College of Chemistry and Environmental Engineering,Yangtze University,Jingzhou 434023,China [2]College of Chemistry and Molecular Sciences,Wuhan University,Wuhan 430072,China [3]College of Chemical Engineering,Northwest University,Xi'an 710069,China

出　　处：《Science China Chemistry》2011年第5期788-796,共9页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China (20873096, 20921062 and 20621502);Fundamental Research Funds for Central Universities (1101007)

摘　　要：The interaction between 3-thiol-4-(2,4-dichlorobenzylideneamino)-5-methyl-4H-1,2,4-triazole (CBTZ) and bovine serum albumin (BSA) under physiological conditions was investigated by fluorescence,UV-vis absorption and circular dichroism (CD) spectroscopy as well as molecular modeling methods. The result of fluorescence experiment indicates the static quenching as a result of the formation of the CBTZ-BSA complex. The binding constants (Ka) at different temperatures were calculated according to the modified Stern-Volmer equation. The enthalpy change (-H) and entropy change (-S) were determined based on the van′t Hoff equation. Both negative-H and-S indicated that van der Waals and hydrogen-bonding forces were the dominant intermolecular forces to stabilize the CBTZ-BSA complex. Site marker competitive replacement experiments demonstrated that binding of CBTZ to BSA primarily took place in sub-domain IIA (Sudlow's site I). The binding distance (r = 7.2 nm) between CBTZ and the tryptophan residue of BSA was estimated according to the theory of fluorescence resonance energy transfer (FRET). The conformational studies by circular dichroism (CD) and three-dimensional fluorescence spectroscopy showed that the presence of CBTZ induced minor changes of the secondary structure of BSA. Molecular modeling study further confirmed the binding mode obtained experimentally.The interaction between 3-thiol-4-（2,4-dichlorobenzylideneamino）-5-methyl-4H-1,2,4-triazole （CBTZ） and bovine serum albumin （BSA） under physiological conditions was investigated by fluorescence,UV-vis absorption and circular dichroism （CD） spectroscopy as well as molecular modeling methods. The result of fluorescence experiment indicates the static quenching as a result of the formation of the CBTZ-BSA complex. The binding constants （Ka） at different temperatures were calculated according to the modified Stern–Volmer equation. The enthalpy change （-H） and entropy change （-S） were determined based on the van′t Hoff equation. Both negative-H and-S indicated that van der Waals and hydrogen-bonding forces were the dominant intermolecular forces to stabilize the CBTZ-BSA complex. Site marker competitive replacement experiments demonstrated that binding of CBTZ to BSA primarily took place in sub-domain IIA （Sudlow’s site I）. The binding distance （r = 7.2 nm） between CBTZ and the tryptophan residue of BSA was estimated according to the theory of fluorescence resonance energy transfer （FRET）. The conformational studies by circular dichroism （CD） and three-dimensional fluorescence spectroscopy showed that the presence of CBTZ induced minor changes of the secondary structure of BSA. Molecular modeling study further confirmed the binding mode obtained experimentally.

关 键 词：TRIAZOLE bovine serum albumin fluorescence quenching binding site molecular modeling 

分 类 号：Q512.1[生物学—生物化学] O641.3[理学—物理化学]