食品科学 ›› 2019, Vol. 40 ›› Issue (16): 75-82.doi: 10.7506/spkx1002-6630-20180727-323

• 食品化学 • 上一篇    下一篇

基于多重光谱技术的木糖醇与牛乳酪蛋白相互作用及对酪蛋白结构的影响

孔繁华,曹雪妍,康世墨,李玮轩,关博元,李墨翰,杨 梅,岳喜庆   

  1. 沈阳农业大学食品学院,辽宁 沈阳 110866
  • 出版日期:2019-08-25 发布日期:2019-08-26
  • 基金资助:
    沈阳市科技计划项目(Y17-0-028)

A Spectroscopic Study of Bovine Casein Structure as Affected by Interaction with Xylitol

KONG Fanhua, CAO Xueyan, KANG Shimo, LI Weixuan, GUAN Boyuan, LI Mohan, YANG Mei, YUE Xiqing   

  1. College of Food Science, Shenyang Agricultural University, Shenyang 110866, China
  • Online:2019-08-25 Published:2019-08-26

摘要: 综合利用荧光光谱法、傅里叶变换红外光谱法和圆二色谱法等多种先进光谱技术研究木糖醇与牛乳酪蛋白的相互作用以及对牛乳酪蛋白二级结构及功能性质的影响。荧光光谱表明,木糖醇对牛乳酪蛋白具有较强的荧光猝灭效应,猝灭机理属于静态猝灭,生成了新的复合物,二者在300、310 K和320 K时相互作用的结合常数分别为5.326×106、2.600×106 L/mol和2.160×106 L/mol,对应的结合位点数分别为1.513、1.452和1.422,主要作用力为静电引力,可能会有疏水作用力,结合距离为3.564 nm;同步荧光光谱和三维荧光光谱的结果表明,二者的相互作用位点更接近于色氨酸,其周围微环境的疏水性增强,使酪蛋白的分子构象发生改变;傅里叶变换红外光谱和圆二色谱的结果表明,木糖醇改变了牛乳酪蛋白的二级结构,使其α-螺旋结构相对含量增加,无规卷曲结构相对含量减少,结构变得更加紧密;结构的变化导致酪蛋白的乳化活性降低,乳化稳定性升高,表面疏水性降低。研究结果为功能性乳基料的开发提供了理论依据。

关键词: 木糖醇, 牛乳酪蛋白, 荧光光谱, 傅里叶变换红外光谱, 圆二色谱

Abstract: In this paper, fluorescence, Fourier transform infrared and circular dichroism spectroscopies were used in conjunction to study the interaction between bovine casein (Cs) and xylitol (XY) and its effect on the structural and functional properties of casein. The results of fluorescence spectroscopy indicated that xylitol strongly quenched the fluorescent intensity of bovine casein. The quenching mechanism was static quenching that generates a new complex. The binding constants for the interaction at 300, 310 and 320 K were 5.326 × 106, 2.600 × 106 and 2.160 × 106 L/mol, respectively, and the binding sites were 1.513, 1.452 and 1.422, respectively. The main binding forces were electrostatic attraction and hydrophobic force with a binding distance of 3.564 nm. The results of synchronous fluorescence and threedimensional fluorescence spectroscopies revealed that the interaction site was closer to the tryptophan residues; this interaction enhanced the hydrophobicity of the surrounding microenvironment and changed the molecular conformation of bovine casein. Fourier transform infrared and circular dichroism spectroscopies showed that xylitol changed the secondary structure of bovine casein by increasing the relative content of α-helix and reducing the relative content of random coil structure and as a result, the structure of bovine casein became more compact. Furthermore, this structural change led to a decrease in the emulsifying activity, an increase in the emulsion stability, and a decrease in the surface hydrophobicity of casein. These results provide a theoretical basis for the development of functional dairy-based ingredients.

Key words: xylitol, bovine casein, fluorescence spectroscopy, Fourier transform infrared spectroscopy, circular dichroism spectroscopy

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