多光谱法研究五种食品色素与BSA的相互作用

发布时间：2018-05-09 14:01

本文选题：食品色素 + 牛血清白蛋白　；参考：《西华师范大学》2017年硕士论文

【摘要】：食品色素常用来维持和改善食品的表观颜色,当其被吸收进入血液循环系统与血清白蛋白结合时,它的分布和自由浓度将受到显著影响,因此,可以通过分析食品色素与蛋白质间的结合特性来获得食品色素的重要信息。酸性红92(AR92)、酸性红26(AR26)、酸性黑1(AB1)、酸性绿9(AG9)和酸性蓝9(AB9)是五种常见食品色素,本文采用多光谱法研究这五种食品色素与牛血清白蛋白(BSA)间的相互作用,并结合-极限理论进行了更深入的分析。探讨在不同p H(4.8、5.5、6.3和7.4;BSA-AR92体系在生理p H即p H 7.4条件下进行研究)和不同温度(293、298、304和310 K)条件下,盐浓度的增加对这五种食品色素与BSA之间相互作用的影响。结果表明BSA-AR92/AR26/AB1/AG9/AB9体系的KSV值与温度呈负相关,对应的Kq值比猝灭剂与生物分子的最大散射碰撞猝灭常数(2.0×1010 L·mol-1·s-1)高,且BSA的RLS光谱强度随AG9/AB9的加入而逐渐增强,暗示这五种食品色素对BSA的荧光猝灭机制均为静态猝灭;同一条件下结合常数K值的大小表明这五种食品色素与BSA结合亲和力遵循以下顺序:AR92AR26AB1AG9AB9,其n值均约为1,表明它们在BSA上有一个独立的结合位点;位点标记物竞争实验表明AR92的结合位点为BSA上的位点I(子域IIA);乙醇对BSA与五种食品色素结合作用的影响进一步确认它们在BSA上有一个特异性结合位点;热力学参数ΔG00,ΔH00,ΔS00暗示BSA与AR92、AR26或AB1间的结合是以静电力为主要驱动力的自发放热过程;对BSA-AG9/AB9体系,在较低盐浓度(离子强度)时静电力是结合作用的主要作用力,当盐浓度增加到一定值时,BSA与AG9/AB9之间的主导力由静电力转变为非静电力(即:氢键作用和范德华力),相互作用时的移动或局部运动因此受阻,同时,从这两个体系观察到焓-熵补偿(EEC);运用-极限理论分析离子强度对BSA-AR26/AB1/AG9/AB9体系结合作用的影响,计算-理论分析参数,结果表明BSA的局部电荷主导BSA-AR26/AB1/AG9/AB9体系的相互作用,而不是它的整体或表面电荷;分析不存在和存在AG9/AB9时Hurea值的变化来探讨BSA的结构稳定性;此外,UV-vis吸收、同步荧光和FT-IR光谱研究结果表明五种食品色素与BSA间的相互作用导致BSA的构象发生改变。
[Abstract]:Food pigment is often used to maintain and improve the apparent color of food. When it is absorbed into the circulatory system and binds to serum albumin, its distribution and free concentration are significantly affected. The important information of food pigments can be obtained by analyzing the binding properties between food pigments and proteins. Acid red 92C AR92N, acidic red 26AAR26, acidic black 1Ab1, acid green 9Ag-AG9) and acid blue 9A9A9) are five common food pigments. The interaction between these five food pigments and bovine serum albumin (BSA) was studied by multispectral method in this paper. And combined with the-limit theory to carry out a more in-depth analysis. The effects of salt concentration on the interaction between the five food pigments and BSA were studied under physiological pH (pH 7.4) and temperature (293298304 and 310K) in different pH 4.85.5K and 7.4 BSA-AR92 systems. The results show that the KSV value of BSA-AR92/AR26/AB1/AG9/AB9 system is negatively correlated with temperature, and the corresponding KQ value is higher than the maximum scattering quenching constant (2.0 脳 1010 L mol-1 s-1) of the quencher and biomolecules, and the RLS spectral intensity of BSA increases with the addition of AG9/AB9. It was suggested that the fluorescence quenching mechanism of the five food pigments to BSA was static quenching. Under the same condition, the binding constant K value indicated that the binding affinity of the five food pigments to BSA followed the following order: AR92AR26AB1AG9AB9, and their n values were about 1, indicating that they had an independent binding site on BSA. The competitive assay of locus marker showed that the binding site of AR92 was IIAA on BSA, and the effect of ethanol on the binding of BSA to five kinds of food pigments confirmed that they had a specific binding site on BSA. The thermodynamic parameters 螖 G _ (00), 螖 H _ (00), 螖 S _ (00) imply that the binding between BSA and AR92N / AR26 or AB1 is a self-releasing heat process driven mainly by static electricity, and that for BSA-AG9/AB9 system, electrostatic force is the main binding force at lower salt concentration (ionic strength). When the concentration of salt increases to a certain value, the dominant force between BSA and AG9/AB9 changes from hydrostatic to non-hydrostatic (i.e. hydrogen bond interaction and van der Waals force), the movement or local movement of the interaction is hindered, and at the same time, Enthalpy entropy compensation was observed in these two systems, the influence of ionic strength on the binding of BSA-AR26/AB1/AG9/AB9 system was analyzed by using the limit theory, and the parameters were calculated and analyzed. The results show that the local charge of BSA dominates the interaction of BSA-AR26/AB1/AG9/AB9 system. Rather than its whole or surface charge, the structural stability of BSA was investigated by analyzing the changes of Hurea values in the absence and presence of AG9/AB9. The results of synchronous fluorescence and FT-IR spectra showed that the interaction of five food pigments with BSA resulted in the conformation change of BSA.
【学位授予单位】：西华师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.3;TS264.4

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