矢车菊素-3-葡萄糖苷与四种乳蛋白相互作用的研究

Study on Interactions between Cyanidin-3-Glucoside and Four Kinds of Milk Proteins

采用荧光光谱法、傅里叶红外光谱法和圆二色谱法,研究矢车菊素-3-葡萄糖苷(cyanidin 3-O-glucoside,C3G)与α-酪蛋白、β-酪蛋白、乳清蛋白和β-乳球蛋白的相互作用。结果表明,C3G对上述四种乳蛋白都产生了荧光静态猝灭作用,在溶液中C3G与乳蛋白相互结合摩尔比约为1∶1,且由热力学参数判定C3G与α-酪蛋白结合的分子间作用力为氢键与范德华力,而与β-酪蛋白、乳清蛋白和β-乳球蛋白结合主要靠静电引力。通过比较C3G与α-酪蛋白、β-酪蛋白、乳清蛋白和β-乳球蛋白相互作用的荧光猝灭率(84%、74%、77%、75%);温度分别为298、318、338 K时的结合常数(423.448、362.994、28.655×10~4L/mol;9.524、8.056、8.308×10~4L/mol;9.262、6.940、7.889×10~4L/mol;30.440、11.830、17.262×10~4L/mol);结合距离(2.17、2.66、2.18、2.19 nm),由此得出α-酪蛋白与C3G结合最紧密。傅里叶红外光谱和圆二色谱分析显示,C3G的加入使得α-酪蛋白的α-螺旋增加,β-折叠和转角降低;β-酪蛋白的α-螺旋、β-折叠和转角均增加;乳清蛋白的α-螺旋、β-折叠和转角均无明显变化;β-乳球蛋白的α-螺旋降低,β-折叠和转角增加。C3G对四种乳蛋白均有较强的结合能力,可以使其构象发生变化。

The interactions between cyanidin- 3 - glucoside （ C3 G） and a- casein,β- casein, whey protein and β- lactoglobulin were studied by fluorescence spectroscopy, fourier transform infrared spectroscopy and circular dichroism. The results showed that C3G had fluorescence static quenching activity on the four kinds of milk proteins,and the combination of C3G with each milk protein was in a molar ratio of 1 ： 1 approximately in the solution.The thermodynamic parameters of the milk protein showed the major binding force between C3G and β-casein was van der Waals forces and hydrogen bonding.The electrostatic attraction played a major role in the interaction between C3G and β - casein/whey protein/β - lactoglobulin. By the comparison of fluorescence quenching rate （ 84% , 74% , 77% , 75% ）, binding constant on 298,318,338 K （ 423.448,362.994,28.655 x 10^4 L/mol. 9.524,8.056,8.308 x 10^4 L/mol. 9.262,6.940,7.889 x 10^4 L/mol. 30.440,11.830,17.262 x 10^4 L/tool）and binding distance （ 2.17,2.66,2.18,2.19 nm） of the interaction on C3 G and a- casein ,β- casein, whey protein ,β- lactoglobulin, it showed that the binding of a-casein and C3G was the most closely. Fourier transform infrared spectrometer and circular dichroism revealed that the addition of C3G increased a- helix, decreased β- sheet and turn angle of a- casein and increased a- helix, β-sheet and turn angle of β-casein. There was no significant changes in the whey protein. The addition of C3G decreased a-helix,increased β-sheet and turn angle of β-lactoglobulin. The results indicated that the interaction between C3G and four kinds of milk proteins was strong,which caused a conformational change of milk proteins.