摘要
目的:探究超声预处理对大豆分离蛋白(soybean protein isolate,SPI)-儿茶素非共价/共价复合物结构及功能的影响。方法:对SPI进行超声处理后,在不同pH值(3.0、7.0、9.0、12.0)下与儿茶素通过非共价/共价结合方式制备复合物,并通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate-polyacrylamide gel electrophoresis,SDS-PAGE)来验证复合物的形成以及蛋白与多酚结合程度,采用荧光光谱法、傅里叶变换红外光谱法及分子对接技术研究SPI与儿茶素之间的相互作用以及SPI结构的变化,通过起泡性、泡沫稳定性、溶解度、浊度及抗氧化能力等指标考察复合物功能性质的变化。结果:SDS-PAGE证实了非共价/共价复合物的形成以及超声预处理对复合物结合程度具有影响,SPI超声后在pH 12时结合的儿茶素最多;荧光光谱和傅里叶变换红外光谱分析结果表明非共价/共价复合物中SPI的二级结构发生改变,与未处理的SPI样品相比,α-螺旋和β-折叠相对含量下降,β-转角和无规卷曲相对含量增加,色氨酸和酪氨酸基团暴露增多,其中pH 12条件下超声预处理效果最显著,β-转角相对含量增加至40.20%,无规卷曲相对含量增加至28.61%,SPI结构变得更加舒展及松散;经超声预处理后,SPI及复合物的溶解度、浊度、起泡性、泡沫稳定性及抗氧化能力均有所增加,其中抗氧化能力提升最显著,在pH 12条件下共价复合物对1,1-二苯基-2-三硝基苯肼自由基清除率提高至未处理SPI样品的5.5倍,对2,2’-联氮-双(3-乙基苯并噻唑啉-6-磺酸)阳离子自由基清除率提高至未处理SPI样品的4.8倍;分子对接结果也验证了SPI与儿茶素非共价结合的作用力主要是氢键和疏水作用。结论:SPI经过超声预处理后在pH 12的条件下与儿茶素结合最强,其共价复合物最稳定,起泡性与抗氧化性得到显著提升。
This study was conducted to explore the effect of ultrasonic pretreatment on the structure and function of non-covalent/covalent complexes of soybean protein isolate(SPI)and catechin.SPI was pretreated with ultrasound before non-covalent/covalent binding to catechin at different pH conditions(3.0,7.0,9.0 and 12.0),Sodium dodecyl sulphate-polyacrylamide gel electrophoresis(SDS-PAGE)was used to verify the formation of complexes and the binding degree between protein and polyphenols.Meanwhile,fluorescence spectroscopy,Fourier transform infrared(FTIR)spectroscopy and molecular docking were used to study the interaction between SPI and catechin.The changes in functional properties of the complexes were investigated in terms of foamability,foam stability,solubility,turbidity,and antioxidant capacity.The SDS-PAGE profile confirmed the formation of non-covalent/covalent complexes,and that ultrasonic pretreatment could affect the degree of binding.It was found that the highest amount of catechin was bound to ultrasonicated SPI at pH 12.Fluorescence and FTIR spectra indicated that the secondary structure of SPI in the non-covalent/covalent complexes was changed.Compared to the untreated SPI sample,the proportions ofα-helix andβ-sheet decreased,the proportions ofβ-turn and random coil increased,and the numbers of exposed tryptophan and tyrosine residues increased.The most significant effect of ultrasonic pretreatment was observed at pH 12;the proportion ofβ-turn increased to 40.20%,the proportion of random coil increased to 28.61%,and SPI’s structure became unfolded and loosened.After ultrasonic pretreatment,compared to the untreated SPI sample,the solubility,turbidity,foamability,foam stability and antioxidant capacity of SPI and complexes increased.In particular,the scavenging capacity against 1,1-diphenyl-2-picrylhydrazine(DPPH)radical and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS)radical cation of complexes formed at pH 12 were up to 5.5 and 4.8 times of the untreated SPI sample,respectively.In addition,the molecular docking results revealed that the main non-covalent binding interactions between SPI and catechin were hydrogen bonds and hydrophobic interactions.To sum up,ultrasonic-treated SPI had the strongest binding strength to catechin at pH 12,and the resulting covalent complex had the best stability as well as significantly improved foamability and antioxidant activity.
作者
代世成
连子腾
马林智
佟晓红
田甜
亓伟杰
彭潮勇
范宇航
王欢
江连洲
DAI Shicheng;LIAN Ziteng;MA Linzhi;TONG Xiaohong;TIAN Tian;QI Weijie;PENG Chaoyong;FAN Yuhang;WANG Huan;JIANG Lianzhou(College of Food Science,Northeast Agricultural University,Harbin 150030,China;Heilongjiang Beidahuang Green Health Food Co.,Ltd.,Jiamusi 154000,China)
出处
《食品科学》
EI
CAS
CSCD
北大核心
2022年第1期102-110,共9页
Food Science
基金
黑龙江省“百千万”工程科技重大专项(2019ZX08B01)
黑龙江省博士后面上资助项目(LBH-Z20089)。
关键词
大豆分离蛋白
儿茶素
超声预处理
非共价/共价结合
功能特性
soybean protein isolate
catechin
ultrasonic pretreatment
non-covalent/covalent binding
functional characteristics