Wheat germ albumin (WGA) has high physicochemical and biological activity after enzymatic hydrolysis. The traditional protease hydrolysis method, due to its low enzymatic efficiency, can no longer meet the needs of efficient production. Adding assisted means to the traditional enzymatic hydrolysis method can improve these shortcomings. In this study, the effect of ultrasonic assisted papain on the hydrolysis degree of WGA and the physicochemical properties and structural characteristics of peptides with different molecular weights (MW) were compared and analyzed. The results showed that the optimal conditions for ultrasonic assisted enzymatic hydrolysis of WGA were determined through Box-Behnken design-response surface methodology (BBD-RSM): hydrolysis time of 20 min, substrate concentration of 2%, papain dosage of 10000 U/g, and ultrasonic power of 180 W. Under this condition, the clearance rate of DPPH could reach 82.29%. After enzymatic hydrolysis β-sheet decreased from 33.74% to 15.64%, β-turn increased from 30.93% to 47.36%, indicating that after enzymatic hydrolysis of WGA, the breaking of peptide bonds lead to the unfolding of the protein secondary structure. The peptides with MW less than 3 kDa exhibited circular particles and a dispersed organizational structure. The peptides with MW less than 3 kDa contained hydrophobic amino acids which could enhance the interaction between different peptides and lipid targets, or allowed peptides to enter target organs through hydrophobic binding. The use of ultrasonic assisted enzymatic hydrolysis of WGA would provide theoretical basis for further industrial application of biologically active wheat germ peptides.

中文翻译：

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超声辅助木瓜蛋白酶水解麦芽白蛋白不同分子量肽的理化性质及结构特征

小麦胚芽清蛋白（WGA）经酶解后具有较高的理化和生物活性。传统的蛋白酶水解方法由于酶解效率低，已不能满足高效生产的需要。在传统的酶解方法中添加辅助手段可以改善这些缺点。本研究比较分析了超声辅助木瓜蛋白酶对WGA水解程度的影响以及不同分子量（MW）肽的理化性质和结构特征。结果表明，通过Box-Behnken设计-响应面法（BBD-RSM）确定了超声辅助酶解WGA的最佳条件：水解时间20 min，底物浓度2%，木瓜蛋白酶用量10000 U/g。 ，超声功率为180 W。在此条件下，DPPH的清除率可达82.29%。酶解后β-折叠从33.74%下降到15.64%，β-转角从30.93%增加到47.36%，表明WGA酶解后肽键断裂导致蛋白质二级结构解折叠。分子量小于3 kDa的肽表现出圆形颗粒和分散的组织结构。分子量小于3 kDa的肽含有疏水性氨基酸，可以增强不同肽与脂质靶点之间的相互作用，或使肽通过疏水性结合进入靶器官。利用超声波辅助酶法水解WGA将为生物活性小麦胚芽肽的进一步工业化应用提供理论基础。