Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur, India.
J Agric Food Chem. 2012 Apr 11;60(14):3727-34. doi: 10.1021/jf205219w. Epub 2012 Mar 29.
Cochineal Red A is a negatively charged synthetic azo food colorant and a potential carcinogen. We present here the study of binding of Cochineal Red A with two homologous serum albumins, human (HSA) and bovine (BSA), in aqueous pH 7.4 buffer by optical spectroscopic techniques. Protein intrinsic fluorescence quenching by Cochineal Red A occurs through ground-state static interaction and its binding with BSA is stronger than with HSA. The magnitudes of thermodynamic parameters suggest that dye binding occurs principally via electrostatic complexation. Site-marker competitive binding shows that Cochineal Red A binds primarily to site I of serum albumins. Circular dichroic spectra indicate that dye binding results in some conformational modification of serum albumins. Increased ionic strength of the medium results in lowering of binding. This study provides an important insight into possible means of removal of dye toxicity.
胭脂红 A 是一种带负电荷的合成偶氮食用色素，也是一种潜在的致癌物质。本研究采用光谱技术，在 pH 值为 7.4 的缓冲水溶液中，研究了胭脂红 A 与两种同源血清白蛋白（人血清白蛋白和牛血清白蛋白）的结合。胭脂红 A 通过基态静态相互作用使蛋白质固有荧光猝灭，其与 BSA 的结合能力强于 HSA。热力学参数表明，染料结合主要通过静电络合发生。位点标记竞争结合表明，胭脂红 A 主要结合于血清白蛋白的 I 位点。圆二色谱表明，染料结合导致血清白蛋白构象发生一定程度的改变。介质离子强度的增加会降低结合。该研究为去除染料毒性提供了重要的见解。
