Zhang Yanyan, Wang Bei, Zhou Cunshan, Atungulu Griffiths G, Xu Kangkang, Ma Haile, Ye Xiaofei, Abdualrahman Mohammed A Y
School of Food and Biological Engineering, Jiangsu University, 301 Xuefu Road, Zhenjiang 212013, China.
Department of Food Science, University of Arkansas Division of Agriculture, 2650 N Young Avenue, Fayetteville, AR 72704, USA.
Ultrason Sonochem. 2016 Jul;31:267-75. doi: 10.1016/j.ultsonch.2015.11.010. Epub 2015 Nov 11.
The effects of alternate dual-frequency ultrasound (ADFU) pretreatment on the degree of hydrolysis (DH) of wheat gluten (WG) and angiotensin I-converting enzyme (ACE) inhibitory activity were investigated in this research. The surface topography, nano-mechanics and secondary structure of WG were also determined using atomic force microscope (AFM) and circular dichroism (CD). The correlations of ACE inhibitory activity and DH with surface topography, nano-mechanics and secondary structure of WG were determined using Pearson's correlation analysis. The results showed that with an increase in either pretreatment duration or power, the ACE inhibitory activity of the hydrolysate also increases, reaching maximum at 10 min and 150 W/L, respectively, and then decreases thereafter. Similarly, AFM analysis showed that as the pretreatment duration or power increases, the surface roughness also increase and again a decrease occurs thereafter. As the pretreatment duration or power increased, the Young's modulus and adhesion of WG also increased and then declined. Young's modulus and adhesions average values were compared with ACE inhibitory activity reversely. The result of the CD spectra analysis exhibited losses in the relative percentage of α-helix of WG. Pearson's correlation analysis showed that the average values of Young's modulus and the relative percentage of α-helix correlated with ACE inhibitory activity of the hydrolysates linearly and significantly (P<0.05); the relative percentage of β-sheet correlated linearly with DH of WG significantly (P<0.05). In conclusion, ADFU pretreatment is an efficient method in proteolysis due to its physical and chemical effect on the Young's modulus, α-helix and β-sheet of WG.
本研究考察了交替双频超声（ADFU）预处理对小麦面筋蛋白（WG）水解度（DH）及血管紧张素I转换酶（ACE）抑制活性的影响。同时利用原子力显微镜（AFM）和圆二色光谱（CD）测定了WG的表面形貌、纳米力学性能及二级结构。采用Pearson相关性分析确定了ACE抑制活性和DH与WG表面形貌、纳米力学性能及二级结构之间的相关性。结果表明，随着预处理时间或功率的增加，水解产物的ACE抑制活性也随之增加，分别在10 min和150 W/L时达到最大值，随后下降。同样，AFM分析表明，随着预处理时间或功率的增加，表面粗糙度也增加，随后再次下降。随着预处理时间或功率的增加，WG的杨氏模量和粘附力也增加，然后下降。杨氏模量和粘附力的平均值与ACE抑制活性呈反向关系。CD光谱分析结果显示WG的α-螺旋相对百分比降低。Pearson相关性分析表明，杨氏模量平均值和α-螺旋相对百分比与水解产物的ACE抑制活性呈显著线性相关（P<0.05）；β-折叠相对百分比与WG的DH呈显著线性相关（P<0.05）。综上所述，ADFU预处理通过对WG的杨氏模量、α-螺旋和β-折叠产生物理和化学作用，是一种有效的蛋白水解方法。
