title: Interaction of (-)-epigallocatechin-3-gallate with human serum albumin: fluorescence, fourier transform infrared, circular dichroism, and docking studies.
abstract: (-)-Epigallocatechin-3-gallate (EGCG), the major constituent of green tea has been reported to prevent many diseases by virtue of its antioxidant properties. The binding of EGCG with human serum albumin (HSA) has been investigated for the first time by using fluorescence, circular dichroism (CD), Fourier transform infrared (FTIR) spectroscopy, and protein-ligand docking. We observed a quenching of fluorescence of HSA in the presence of EGCG. The binding parameters were determined by a Scatchard plot and the results were found to be consistent with those obtained from a modified Stern-Volmer equation. From the thermodynamic parameters calculated according to the van't Hoff equation, the enthalpy change deltaH degrees and entropy change deltaS degrees were found to be -22.59 and 16.23 J/mol K, respectively. These values suggest that apart from an initial hydrophobic association, the complex is held together by van der Waals interactions and hydrogen bonding. Data obtained by fluorescence spectroscopy, CD, and FTIR experiments along with the docking studies suggest that EGCG binds to residues located in subdomains IIa and IIIa of HSA. Specific interactions are observed with residues Trp 214, Arg 218, Gln 221, Asn 295 and Asp 451. We have also looked at changes in the accessible surface area of the interacting residues on binding EGCG for a better understanding of the interaction.
authors.affiliation: Department of Chemistry, Indian Institute of Technology, Kharagpur, India.
authors.forename: Tushar Kanti
authors.initials: TK
authors.lastname: Maiti
authors.forename: Kalyan Sundar
authors.initials: KS
authors.lastname: Ghosh
authors.forename: Swagata
authors.initials: S
authors.lastname: Dasgupta
mesh_terms: D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D002942:Circular Dichroism / Q000379:methods; D006801:Humans; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013816:Thermodynamics
chemical_list: D012709:Serum Albumin; D002392:Catechin; C045651:epigallocatechin gallate