title: Mechanistic and conformational studies on the interaction of food dye amaranth with human serum albumin by multispectroscopic methods.
abstract: The mechanism of interaction between food dye amaranth and human serum albumin (HSA) in physiological buffer (pH 7.4) was investigated by fluorescence, UV-vis absorption, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopy. Results obtained from analysis of fluorescence spectra indicated that amaranth had a strong ability to quench the intrinsic fluorescence of HSA through a static quenching procedure. The negative value of enthalpy change and positive value of entropy change elucidated that the binding of amaranth to HSA was driven mainly by hydrophobic and hydrogen bonding interactions. The surface hydrophobicity of HSA increased after binding with amaranth. The binding distance between HSA and amaranth was estimated to be 3.03 nm and subdomain IIA (Sudlow site I) was the primary binding site for amaranth on HSA. The results of CD and FT-IR spectra showed that binding of amaranth to HSA induced conformational changes of HSA.
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, No. 235 Nanjing East Road, Nanchang 330047, Jiangxi, China. gwzhang@ncu.edu.cn
authors.forename: Guowen
authors.initials: G
authors.lastname: Zhang
authors.forename: Yadi
authors.initials: Y
authors.lastname: Ma
mesh_terms: D000548:Amaranth Dye / Q000737:chemistry*; D005505:Food Coloring Agents / Q000737:chemistry*; D006801:Humans; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D012709:Serum Albumin / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D005505:Food Coloring Agents; D012709:Serum Albumin; D000548:Amaranth Dye