Interaction between an (-)-epigallocatechin-3-gallate-copper complex and bovine serum albumin: Fluorescence, circular dichroism, HPLC, and docking studies. 2019

Liangliang Zhang, and Yuchen Liu, and Yongmei Wang
Institute of Chemical Industry of Forest Products, CAF, Nanjing 210042, China; Key Lab. of Biomass Energy and Material, Nanjing, Jiangsu Province 210042, China; Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210042, China. Electronic address: zhll20086@163.com.

The interaction of copper complexed with (-)-epigallocatechin-3-gallate (EGCG) and bovine serum albumin (BSA) was investigated using fluorescence, circular dichroism (CD) spectroscopy, HPLC and protein-ligand docking. The fluorescence quenching efficiency of BSA by EGCG was enhanced after EGCG was complexed with copper, and the EGCG-Cu complex exhibited a higher apparent binding affinity (8.88 × 105 M-1) to BSA compared with EGCG alone (5.17 × 105 M-1). The CD experiment showed that both the EGCG-BSA and [EGCG-Cu]-BSA interactions resulted in the unfolding of the secondary structure of the protein. Results of competitive binding experiments confirmed that the location of EGCG and EGCG-Cu complex binding in BSA was site I. Furthermore, molecular modeling was used to identify the amino acid residue in site I and site II that play key roles in this binding interaction. The data suggest that most of the residues involved in the [EGCG-Cu]-BSA reaction belong to the subdomains IIa (site I) of BSA.

UI MeSH Term Description Entries
D008024 Ligands A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed) Ligand
D002392 Catechin An antioxidant flavonoid, occurring especially in woody plants as both (+)-catechin and (-)-epicatechin (cis) forms. Catechinic Acid,Catechuic Acid,(+)-Catechin,(+)-Cyanidanol,(+)-Cyanidanol-3,(-)-Epicatechin,(2R,3R)-2-(3,4-Dihydroxyphenyl)-3,5,7-chromanetriol,2H-1-Benzopyran-3,5,7-triol, 2-(3,4-dihydroxyphenyl)-3,4-dihydro-, (2R-cis)-,3,3',4',5,7-Flavanpentol,Catergen,Cianidanol,Cyanidanol-3,Epicatechin,KB-53,Z 7300,Zyma,Cyanidanol 3,KB 53,KB53
D002851 Chromatography, High Pressure Liquid Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed. Chromatography, High Performance Liquid,Chromatography, High Speed Liquid,Chromatography, Liquid, High Pressure,HPLC,High Performance Liquid Chromatography,High-Performance Liquid Chromatography,UPLC,Ultra Performance Liquid Chromatography,Chromatography, High-Performance Liquid,High-Performance Liquid Chromatographies,Liquid Chromatography, High-Performance
D002942 Circular Dichroism A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Circular Dichroism, Vibrational,Dichroism, Circular,Vibrational Circular Dichroism
D003300 Copper A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55. Copper-63,Copper 63
D001667 Binding, Competitive The interaction of two or more substrates or ligands with the same binding site. The displacement of one by the other is used in quantitative and selective affinity measurements. Competitive Binding
D012710 Serum Albumin, Bovine Serum albumin from cows, commonly used in in vitro biological studies. (From Stedman, 25th ed) Fetal Bovine Serum,Fetal Calf Serum,Albumin Bovine,Bovine Albumin,Bovine Serum Albumin,Albumin, Bovine,Albumin, Bovine Serum,Bovine Serum, Fetal,Bovine, Albumin,Calf Serum, Fetal,Serum, Fetal Bovine,Serum, Fetal Calf
D013050 Spectrometry, Fluorescence Measurement of the intensity and quality of fluorescence. Fluorescence Spectrophotometry,Fluorescence Spectroscopy,Spectrofluorometry,Fluorescence Spectrometry,Spectrophotometry, Fluorescence,Spectroscopy, Fluorescence
D017433 Protein Structure, Secondary The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to ALPHA-HELICES; BETA-STRANDS (which align to form BETA-SHEETS), or other types of coils. This is the first folding level of protein conformation. Secondary Protein Structure,Protein Structures, Secondary,Secondary Protein Structures,Structure, Secondary Protein,Structures, Secondary Protein
D056831 Coordination Complexes Neutral or negatively charged ligands bonded to metal cations or neutral atoms. The number of ligand atoms to which the metal center is directly bonded is the metal cation's coordination number, and this number is always greater than the regular valence or oxidation number of the metal. A coordination complex can be negative, neutral, or positively charged. Metal Complexes,Complexes, Coordination,Complexes, Metal

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