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本研究利用拉曼光谱技术分析了超声处理及高压均质作用下大豆蛋白-磷脂酰胆碱复合物结构的变化规律。研究表明超声处理及高压均质处理均提高了大豆蛋白α-螺旋结构及无规则卷曲结构含量,并降低了大豆蛋白的β-构型结构。大豆蛋白-磷脂酰胆碱交互作用显著降低了蛋白质α-螺旋结构,并转变为无规则卷曲结构及β-折叠结构。超声处理及高压均质作用下大豆蛋白-磷脂酰胆碱复合物中蛋白质α-螺旋结构均低于高速分散处理组,而β-折叠结构及无规卷曲结构含量较高。超声处理、高压均质作用下大豆蛋白色氨酸、酪氨酸残基趋于“暴露态”,促进了与磷脂酰胆碱之间的疏水交互作用。大豆蛋白-磷脂酰胆碱的交互作用位点为大豆蛋白疏水氨基酸侧链及磷脂酰胆碱疏水脂链,两者之间的疏水作用是大豆蛋白-磷脂酰胆碱交互作用的主要形式。超声处理、高压均质作用下大豆蛋白二硫键构型未发生显著变化,仍保持旁-旁-反式(gauche-gauche-trans,g-g-t)构象振动模式。大豆蛋白-磷脂酰胆碱交互作用亦未改变二硫键构型。
In this study, the change of structure of soybean protein-phosphatidylcholine complex under ultrasonic treatment and high-pressure homogenization was analyzed by Raman spectroscopy. The results showed that both ultrasonic treatment and high pressure homogenization treatment increased the content of α-helix and random coil in soybean protein and reduced the β-configuration of soybean protein. Soybean protein - phosphatidylcholine interaction significantly reduced the protein α-helix structure, and transformed into irregular curly structure and β-sheet structure. The protein α-helical structure of soybean protein-phosphatidylcholine complex under ultrasonic treatment and high-pressure homogenization was lower than high-speed dispersion treatment group, while β-sheet structure and random coil structure content were higher. Soy protein tryptophan and tyrosine residues tended to be “exposed” under ultrasonic treatment and high pressure homogenization, which promoted the hydrophobic interaction with phosphatidylcholine. Soybean protein - phosphatidylcholine interaction site for the soy protein hydrophobic amino acid side chains and phosphatidylcholine hydrophobic lipid chain, the hydrophobic interaction between the two is the main form of soy protein - phosphatidylcholine interaction. Under ultrasonic treatment and high pressure homogenization, the disulfide bond configuration of soybean protein did not change significantly, and the g-g-t conformational vibration mode remained. Soy protein - phosphatidylcholine interaction also did not change the disulfide bond configuration.