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Binding of methacycline to human serum albumin at subdomain IIA using multispectroscopic and molecular modeling methods
Author(s) -
Dong Chengyu,
Lu Ningning,
Liu Ying
Publication year - 2012
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.2462
Subject(s) - chemistry , human serum albumin , hydrogen bond , quenching (fluorescence) , fluorescence , enthalpy , fourier transform infrared spectroscopy , van der waals force , förster resonance energy transfer , protein secondary structure , binding site , analytical chemistry (journal) , spectroscopy , molecule , chromatography , organic chemistry , biochemistry , thermodynamics , physics , quantum mechanics
This study was designed to examine the interaction of methacyline (METC) with human serum albumin (HSA) by multispectroscopy and a molecular modeling method under simulative physiological conditions. The quenching mechanism was suggested to be static quenching based on fluorescence and ultraviolet–visible (UV–Vis) spectroscopy. According to the Vant' Hoff equation, the values of enthalpy (∆ H ) and entropy change (∆ S ) were calculated to be −95.29 kJ/mol and −218.13 J/mol/K, indicating that the main driving force of the interaction between HSA and METC were hydrogen bonds and van der Waals's forces. By performing displacement measurements, the specific binding of METC in the vicinity of Sudlow's site I of HSA was clarified. An apparent distance of 3.05 nm between Trp214 and METC was obtained via the fluorescence resonance energy transfer (FRET) method. Furthermore, the binding details between METC and HSA were further confirmed by molecular docking studies, which revealed that METC was bound at subdomain IIA through multiple interactions, such as hydrophobic effect, polar forces, hydrogen bonding, etc. The results of three‐dimensional fluorescence and Fourier transform infrared (FTIR) spectroscopy showed that METC caused conformational and some microenvironmental changes in HSA and reduced the α‐helix significantly in the range of 52.3−40.4% in HSA secondary structure. Moreover, the coexistence of metal ions such as Ca 2+ , Al 3+ , Fe 3+ , Zn 2+ , Cu 2+ , Cr 3+ and Cd 2+ can decrease the binding constants of METC–HSA. Copyright © 2012 John Wiley & Sons, Ltd.