Department of Chemistry, Indian Institute of Technology Kharagpur, Kharagpur 721 302, India.
J Photochem Photobiol B. 2013 Jul 5;124:50-62. doi: 10.1016/j.jphotobiol.2013.04.004. Epub 2013 Apr 18.
Here we have investigated the binding of carmoisine, a water-soluble azo food colorant, with serum proteins (HSA and BSA) by fluorescence and UV-VIS spectroscopy, circular dichroism and molecular docking studies. Results indicate that fluorescence quenching of protein has been due to site-specific binding of the dye with biomacromolecules. Site marker competitive binding and molecular docking explorations show that interaction occurs in the sub-domain ІІA of HSA and the sub-domains ІІA and ІB in the case of BSA. Conformational investigation indicates that dye binding modifies the secondary structure of proteins and this also alters the microenvironment of the tryptophan(s). The interaction is found to be pH-insensitive which can have relevance to the toxicological profiles of the dye, and ionic strength dependence of binding can be exploited in protein purification mediated by such food colorants.
本研究采用荧光光谱、紫外可见光谱、圆二色性和分子对接等方法，考察了水溶性偶氮类食用色素丽春红 4R 与血清蛋白（HSA 和 BSA）的结合情况。结果表明，荧光猝灭是由于该染料与生物大分子的特异性结合所致。通过位点标记竞争结合和分子对接研究发现，该相互作用发生在 HSA 的亚域ⅡA 和 BSA 的亚域ⅡA 和 IB 中。构象研究表明，染料结合会改变蛋白质的二级结构，进而改变色氨酸的微环境。研究发现，这种相互作用对 pH 不敏感，这可能与该染料的毒理学特征有关，而且结合的离子强度依赖性可用于此类食用色素介导的蛋白质纯化。
