花生蛋白的浓度对其超声改性效果的影响

Effect of peanut protein concentration on its ultrasonic modification

超声处理可以改变蛋白结构从而改善其功能特性,而蛋白与水的质量体积比(以下简称蛋白浓度)会影响蛋白改性效果,通过改变体系中的花生蛋白浓度(0.005~0.150 g/mL),采用十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)、荧光光谱、傅里叶红外光谱、高效液相色谱分析花生蛋白的亚基组成、表面疏水性、内源荧光发射波长、二级结构和分子量,研究其对花生蛋白分子结构的影响。结果表明:较高浓度(0.1 g/mL)的花生蛋白经超声(400 W,5 min)处理后表面疏水性和暴露游离巯基含量显著增加,内源荧光发射波长发生了明显红移,而且平均粒径增加幅度最大,但超声强度增加后平均粒径降低;较低浓度(0.01 g/mL)的花生蛋白经超声处理后二硫键含量最高,二级结构变化较大,表现在β-折叠含量显著下降,β-转角含量显著增加。因此,为达到某项分子结构的预期改性目标,超声时选择合适的蛋白浓度至关重要。

To explore the influence of the protein mass volume percentage concentration(hereinafter referred to as the concentration)in the ultrasound system on the modification effect,in this paper,different concentrations of peanut protein were prepared and ultrasonic treatment was conducted.The subunit composition,surface hydrophobicity,endogenous fluorescence emission wavelength,secondary structure and molecular weight of peanut proteins were analyzed by SDS-PAGE,fluorescence spectrum,Fourier transform infrared spectrum and high performance liquid chromatography,respectively.Through the above structural analysis,it was found that the composition and the primary structure of peanut protein was not changed by ultrasonic treatment.After ultrasonic treatment(400 W,5 min),the surface hydrophobicity and exposed sulfhydryl group content of peanut protein with a higher concentration(0.1 g/mL)were significantly increased,the wavelength of endogenous fluorescence emission was redshifted obviously,and the average particle size increased the most,but the particle size decreased with the increase of ultrasonic intensity.By high performance liquid chromatography(HPLC)determination,it was found that after ultrasonic processing,large molecular weight protein was formed,besides,peanut protein also contained a few lower molecular weight components,indicating that peanut protein subunits were aggregated and a small amount of protein subunits from original oligomers dissociated.The content of disulfide bond was the highest in peanut protein with a lower concentration(0.01 g/mL)after ultrasonic treatment,and the secondary structure changed significantly,showing that the content of β-sheet significantly decreased,and the content of β-turn significantly increased.Therefore,in order to achieve a desired modification target of a molecular structure,it is very important to select an appropriate protein concentration during ultrasound.