Interactions of two food colourants with BSA: Analysis by Debye-Hückel theory.
We have focused on exploring pH- and ionic strength-modulated binding of acid red 1 (AR1) and acid green 50 (AG50) with bovine serum albumin (BSA) by fluorescence, UV-vis absorption and FTIR spectra. The results implied that the quenching mechanism of BSA-AR1/AG50 system was a static quenching, electrostatic force dominated the formation of BSA-AR1/AG50 complex, and the binding affinity of AR1 was greater than that of AG50 on the subdomain IIA of BSA. Moreover, their true thermodynamic binding constant (Keq), true free energy change (ΔG(0)I→0), and effective charge (ZP) in the anion receptor pocket of BSA were calculated using Debye-Hückel limiting law. The local charge bound by AR1/AG50 rather than the overall or surface charge of BSA played a key role in determining their interaction strength. Besides, the thermal and structural stabilization of BSA was discussed by analyzing the changes of Tm and Hurea without/with the addition of AR1/AG50, respectively.
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637002, PR China.
Tian
T
Li
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637002, PR China. Electronic address: ncczj1112@126.com.
Zhengjun
Z
Cheng
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637002, PR China.
Lijun
L
Cao
Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province, China West Normal University, Nanchong 637002, PR China.
Xiaohui
X
Jiang
School of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, PR China. Electronic address: fanlei@yzu.edu.cn.
Lei
L
Fan
D000818:Animals; D000838:Anions; D002417:Cattle; D005290:Ferric Compounds / Q000737:chemistry*; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D005504:Food Analysis / Q000379:methods*; D005505:Food Coloring Agents / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009282:Naphthalenesulfonates / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D055672:Static Electricity; D013696:Temperature; D013816:Thermodynamics
D000838:Anions; D005290:Ferric Compounds; D005456:Fluorescent Dyes; D005505:Food Coloring Agents; D009282:Naphthalenesulfonates; D012710:Serum Albumin, Bovine; D012965:Sodium Chloride; C574940:naphthol green B
Acid green 50; Acid green 50 (PubChem CID: 91525); Acid red 1; Acid red 1 (PubChem CID: 6507024); Binding characteristic; Bovine serum albumin; Debye-Hückel theory; Disodium hydrogen phosphate (PubChem CID: 24203); Ethanol (PubChem CID: 702); Sodium chloride (PubChem CID: 5234); Sodium dihydrogen orthophosphate (PubChem CID: 23672064)