Binding of human serum albumin to N-(p-ethoxy-phenyl)-N'-(1-naphthyl)thiourea and synchronous fluorescence determination of human serum albumin.
The binding of N-(p-ethoxy-phenyl)-N'-(1-naphthyl)thiourea (EPNT) to human serum albumin (HSA) was investigated under simulative physiological conditions by fluorescence spectra in combination with UV absorption spectroscopy and a molecular modeling method. A strong fluorescence quenching reaction of EPNT to HSA was observed, and the quenching mechanism was suggested to be static quenching according to the Stern-Volmer equation. The binding constants (K) at different temperatures as well as thermodynamic parameters, enthalpy change (DeltaH) and entropy change (DeltaS), were calculated according to relevant fluorescent data and the vant' Hoff equation. This indicated that a hydrophobic interaction was a predominant intermolecular force for stabilizing the complex, which is in agreement with the results of molecule modeling study. The effects of energy transfer and other ions on the binding constant were considered. In addition, synchronous fluorescence technology was successfully applied to the determination of HSA added into the EPNT solution.
Cui
Fengling
F
School of Chemistry and Environmental Science, Key Laboratory for Environmental Pollution Control Technology of Henan Province, Henan Normal University, People's Repblic of China. fenglingcui@hotmail.com
Wang
Junli
J
Cui
Yanrui
Y
Li
Jianping
J
Lu
Yan
Y
Fan
Jing
J
Yao
Xiaojun
X
D000465:Algorithms; D000838:Anions / Q000737:chemistry; D002021:Buffers; D002412:Cations / Q000737:chemistry; D004735:Energy Transfer; D005019:Ethyl Ethers / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009281:Naphthalenes / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D012709:Serum Albumin / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet; D013696:Temperature; D013816:Thermodynamics; D013890:Thiourea / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism
D000838:Anions; D002021:Buffers; D002412:Cations; D005019:Ethyl Ethers; D009281:Naphthalenes; D012709:Serum Albumin; D013890:Thiourea