pH酸性偏移结合热处理对米糠蛋白结构的影响

Effect of Acidic pH-Shifting Combined with Heat Treatment on The Structure of Rice Bran Protein

研究pH酸性偏移(pH 1.5)结合热处理(50、60℃)对米糠蛋白结构的影响。结果表明,pH酸性偏移使得米糠蛋白部分无规卷曲和β-转角结构展开,形成氨基酸侧链;结合热处理时,随着处理时间的延长,米糠蛋白二级结构呈现去折叠-复折叠的复杂变化。pH酸性偏移使得米糠蛋白巯基氧化,热处理会加剧米糠蛋白巯基氧化程度。分子量分布、蛋白质电泳和内源荧光光谱结果表明,pH酸性偏移使得米糠蛋白聚集体解离;而结合热处理后,随着处理时间的延长,米糠蛋白又会通过疏水相互作用或氧化作用形成聚集体。表面疏水性和溶解性的变化进一步说明了米糠蛋白在pH酸性偏移结合热处理过程中的分子展开-聚集行为。

The effects of acidic pH-shifting(pH 1.5)combined with heat treatment(50 and 60℃)on the structural characteristics of rice bran protein were studied in detail.The results indicated that the amino acid side chains could be formed with the acidic pH-shifting resulting in unfolding of partial random coil andβ-turn structures.With the processing time extension,acidic pH-shifting combined with heat treatment presented complex changes of unfolding-refolding of the secondary structure of rice bran protein.Acidic pH-shifting resulted in oxidation of sulfhydryl groups of rice bran protein.Acidic pH-shifting combined with heat treatment could accelerate oxidation extent of sulfhydryl groups.The results of molecular weight distribution,electrophoresis,and intrinsic fluorescence spectra of rice bran protein indicated that acidic pH-shifting resulted in dissociation of rice bran protein aggregates.With the processing time extension,acidic pH-shifting combined with heat treatment lead to rice bran protein aggregate through hydrophobic interaction or oxidative modification.Unfolding and aggregation behavior of rice bran protein during the acidic pH-shifting combined with heat treatment was further confirmed by the change of surface hydrophobicity and solubility of rice bran protein.