title: Characterisation of interaction between food colourant allura red AC and human serum albumin: multispectroscopic analyses and docking simulations.
abstract: Binding interaction of human serum albumin (HSA) with allura red AC, a food colourant, was investigated at the molecular level through fluorescence, ultraviolet-visible, circular dichroism (CD) and Raman spectroscopies, as well as protein-ligand docking studies to better understand the chemical absorption, distribution and transportation of colourants. Results show that allura red AC has the ability to quench the intrinsic fluorescence of HSA through static quenching. The negative values of the thermodynamic parameters ΔG, ΔH, and ΔS indicated that hydrogen bond and van der Waals forces are dominant in the binding between the food colourant and HSA. The CD and Raman spectra showed that the binding of allura red AC to HSA induces the rearrangement of the carbonyl hydrogen-bonding network of polypeptides, which changes the HSA secondary structure. This colourant is bound to HSA in site I, and the binding mode was further analysed with the use of the CDOCKER algorithm in Discovery Studio.
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu 610065, China.
authors.forename: Di
authors.initials: D
authors.lastname: Wu
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu 610065, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Yan
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu 610065, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu 610065, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Wang
authors.affiliation: College of Chemical Engineering, Sichuan University, Chengdu 610065, China. Electronic address: lihuilab@sina.com.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D005505:Food Coloring Agents / Q000737:chemistry*; D006801:Humans; D062105:Molecular Docking Simulation; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012709:Serum Albumin / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013057:Spectrum Analysis / Q000379:methods*; D013816:Thermodynamics
chemical_list: D001391:Azo Compounds; D005505:Food Coloring Agents; D012709:Serum Albumin; C005915:Allura Red AC Dye
keywords: Allura red AC; Circular dichroism; Fluorescence quenching; HSA; Molecular modelling; Raman spectrum