Sudan III is a coloring agent used in chemical industries and food additives. This article uses spectroscopic and molecular docking methods to investigate the interaction of Sudan III with bovine serum albumin (BSA) under a physiological condition. Spectroscopic analysis of the emission quenching revealed that the quenching mechanism of BSA by Sudan III was static. The binding sites and constants of Sudan III-BSA complex were observed to be from 0.72 and 6.41 × 102 L·mol-1 to 0.69 and 5.83 × 102 L·mol-1 at 298 and 310 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) revealed that van der Waals forces and hydrogen bonds stabilized the Sudan III-BSA complex. Energy transfer from tryptophan to Sudan III occurred by a fluorescence resonance energy transfer mechanism, and the r distance (3.32 nm) had been determined. The results of UV-Vis absorption, synchronous, three-dimensional fluorescence, and circular dichroism spectra showed that Sudan III induced conformational changes of BSA. Molecular docking studies revealed that Sudan III situated within subdomain IIA of BSA. A study on the interaction between Sudan III and BSA was of fundamental importance for providing more information about the potential toxicological effect of chemicals at the molecular level.

中文翻译：

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用光谱和分子对接方法研究食用色素Sudan III与牛血清白蛋白的相互作用。

Sudan III是用于化学工业和食品添加剂的着色剂。本文使用光谱和分子对接方法研究了苏丹III在生理条件下与牛血清白蛋白（BSA）的相互作用。发射猝灭的光谱分析表明，苏丹III对BSA的猝灭机理是静态的。苏丹III-BSA复合物的结合位点和常数在298 K和310 K下分别为0.72和6.41×102 L·mol-1至0.69和5.83×102 L·mol-1。焓变（ΔH）和熵变（ΔS）表明范德华力和氢键稳定了苏丹III-BSA配合物。从色氨酸到苏丹III的能量转移是通过荧光共振能量转移机制发生的，并且r距离（3.32 nm）已经确定。紫外-可见吸收，同步，三维荧光和圆二色性光谱的结果表明，苏丹III诱导了牛血清白蛋白的构象变化。分子对接研究表明，苏丹III位于BSA的IIA亚域内。苏丹III和BSA之间相互作用的研究对于提供更多有关分子水平上化学物质潜在毒理作用的信息至关重要。