亚油酸氧化诱导大豆分离蛋白氧化对其结构的影响

Effect of protein oxidation induced by linoleic acid oxidation on the structure of soy protein isolate

利用脂肪氧合酶催化不同底物浓度亚油酸氧化大豆分离蛋白,通过测定氧化后大豆分离蛋白的羰基值、巯基、表面疏水性、内源荧光以及凝胶电泳等指标,对氧化修饰后大豆分离蛋白的结构进行分析,并通过分析氧化后大豆分离蛋白在不同溶剂中溶解性能表征其分子间相互作用力。结果表明,随体系中亚油酸浓度的增加,大豆分离蛋白羰基含量增加56.3%,总巯基和游离巯基含量降低,表面疏水性呈先增大后减小趋势,内源荧光强度降低,发生先红移后蓝移现象,大豆分离蛋白粒径先减小后增大,主要分布于5~40 nm之间,蛋白质氧化过程发生去折叠和重聚集,蛋白质交联中存在非二硫键共价键生成。

Soy protein isolate （SPI） oxidation was induced by lipoxygenase-catalyzed linoleic acid. Protein carbonyl content, suhfhydryl content, surface hydropbobicity, intrinsic fluorescence, and gel electrophoresis were tested to evaluate the effect of protein oxidation of SPI. The solubility of SPI in different solvents was also analyzed to elabo- rate the inter- and intra-molecular interactions. Results indicated that with the increase of linoleic acid substrate, carbonyl value significantly increased, total sulfhydryl and free sulfhydryl group content decreased, surface hydrophobicity increased and then decreased, intrinsic fluorescence decreased, red shift of SPI was first observed and then blue shifted, the particle size of SPI decreased and then increased and was in the range 5 -40 nm. The SPI oxidation caused protein unfolding and aggregation, and non-disulfide covalent bond generated.