马铃薯蛋白酶抑制剂酶解产物超滤组分的抗氧化活性与结构特征

Antioxidant and Structural Characteristics of Ultrafiltration Components from Enzymatic Hydrolysates of Potato Protease Inhibitors

超声波联合蛋白酶K酶解马铃薯蛋白酶抑制剂,研究酶解产物(PPIHs)的理化性质、抗氧化稳定性及其超滤后各组分的抗氧化活性及结构特性。结果表明,超声联合酶解处理后,PPIHs的溶解度和乳化及乳化稳定性增强;抗氧化稳定性在80℃以下较好,超过80℃有下降趋势;在酸性或非碱性环境下,除对ABTS自由基的抗氧化稳定性较差,PPIHs对其他自由基的抗氧化稳定性较好。PPIHs经过超滤得到PPIHs-Ⅰ(>10 ku)、PPIHs-Ⅱ(3~10 ku)和PPIHs-Ⅲ(<3 ku)3种超滤产物,PPIHs-I对ABTS自由基的清除能力最强,Zeta电位的绝对值显著增大;PPIHs-II的抑制油脂氧化以及对-OH和DPPH自由基的清除能力较强,粒径显著减小。紫外吸收光谱、红外光谱和荧光光谱表明,酶解产物的结构发生改变,如无规卷曲和β-转角含量提高,β-折叠和α-螺旋减少,疏水性增强等,进而改善其抗氧化活性。

Ultrasonic combined with proteinase K enzymatic digestion of potato protease inhibitors was used to study the physicochemical properties,antioxidant stability of the enzymatic digestion products(PPIHs)and the antioxidant activity and structural properties of each fraction after ultrafiltration.The results indicated that the solubility and emulsification and emulsion stability of PPIHs were enhanced after combined enzymatic treatment with ultrasound;the antioxidant stability was better below 80℃and tended to decrease above 80℃;the antioxidant stability of PPIHs was better against other free radicals under acidic or non-alkaline environment,except for the poor antioxidant stability against ABTS free radicals.PPIHs were obtained by ultrafiltration PPIHs-Ⅰ(>10 ku),PPIHs-Ⅱ(3~10 ku)and PPIHs-Ⅲ(<3 ku)were obtained by ultrafiltration.PPIHs-I had the strongest scavenging ability for ABTS radicals and the absolute value of zeta potential increased significantly;PPIHs-II had a stronger ability to inhibit lipid oxidation and scavenge-OH and DPPH radicals,and the particle size decreased significantly.The particle size was significantly reduced.The UV absorption spectra,IR spectra and fluorescence spectra showed that the structure of the enzymatic products was changed,such as the increase of random curl andβ-turn angle content,the decrease ofβ-folding andα-helix,and the increase of hydrophobicity,which in turn improved their antioxidant activity.