高压处理对花生分离蛋白凝胶特性和分子结构的影响

Effects of High Pressure on the Gelatin Properties and Molecular Structure of Peanut Protein Isolates

本文研究了质量浓度为5%的花生分离蛋白(PPI)在50-200 MPa压力范围处理5 min后的热凝胶硬度、弹性和粘结力的变化情况,并对处理前后的PPI进行了SDS-PAGE、圆二色谱(CD)、质谱和分子结构模拟分析。SDS-PAGE电泳结果表明,PPI中分子量为61.0 ku的亚基对压力最敏感,对此亚基进行质谱分析,结果表明压力处理后,此亚基的氨基酸序列未发生变化,含580个氨基酸,实际分子量为66.5 ku,为伴花生球蛋白Ⅱ的电泳条带,在此基础上进行分子模拟,发现其空间构象在100 MPa处理后发生了显著变化。CD结果表明,高压处理后,PPI的二级构象发生了显著变化。PPI热凝性结果表明,100 MPa处理后其形成的热凝胶硬度最大,为172 g,比未处理提高了49.6%,弹性和粘结力与未处理相当。以上结果说明压力处理使得PPI热凝胶特性得到了改善。

The change of heat-induced gelatin hardness, springiness and cohesiveness of PPI （5%） treated under pressure 50-200 MPa for 5 min were investigated and compared with the untreated PPI by various methods including SDS-PAGE, circular dichroism spectra, mass spectrometry and estimation analysis of molecular structure. SDS-PAGE analysis indicated a subunit known as conarachin II whit molecular weight 61.0 ku was more sensitive to pressure, and mass spectrometry analysis shown this subunit contained 580 amino acids whose sequence was not changed after pressure treatment and its actual molecular weight was 66.5 ku. Estimation analysis of molecular structure of this unit showed its steric conformation was significantly changed after pressure 100 MPa treatment. Results from CD showed a secondary structure of PPI also greatly changed under high pressure treatment. PPI treated under 100 MPa resulted in the largest value for heat-induced gelatin hardness, increased by 49.6% compared with untreated PPI and reached 172 g, while springiness and cohesiveness remained equal to that of untreated. All the findings above indicated pressure treatment can improve heat-induced gelatin properties of PPI.