氧化对肌原纤维蛋白流变学特性及结构的影响

以鸡肉肌原纤维蛋白(myofibrillar protein,MP)作为研究对象,利用脂肪氧化酶-亚油酸体系研究了蛋白质氧化对MP加热过程中的流变性质、凝胶状态下的二级结构和疏水相互作用的影响,并探讨了加热过程中的流变性质、凝胶状态下蛋白质的二级结构与疏水相互作用的内在联系。研究表明,与其他亚油酸浓度处理的样品相比,亚油酸浓度为2 mmol/L的MP样品的G′值(>68℃)最大。随着亚油酸的加入,α-螺旋含量从未氧化时的48.31%一直降低到亚油酸10 mmol/L时的最低值29.57%,而β-折叠含量则从14.75%缓慢升高到22.14%,β-转角含量也随着氧化程度的升高,从16.28%增加到21.88%,无规则卷曲的含量总体呈现升高的趋势。随着氧化程度的升高,MP凝胶的疏水相互作用先增加后降低,在2 mmol/L达到最大值,同时G′值(>68℃)在2 mmol/L时达到最大,这表明疏水相互作用的变化与MP凝胶中蛋白质二级结构的变化具有密切的相关性。

Effect of Oxidation on Rheological Properties and Structure of Myofibrillar Protein

The study was designed to reveal the effect of protein oxidation on rheological properties during heating,hydrophobic interaction and secondary structure of chicken myofibrillar protein(MP)gel using lipoxygenase-linoleic acid system.The internal relationship between MP rheological properties during heating,protein secondary structure in gel state and hydrophobic interaction was revealed.The results showed that,MP samples with a linoleic acid concentration of 2 mmol/L had the largest G′value(>68℃)compared with other linoleic acid concentrations.With the addition of linoleic acid,theα-helix content decreased from 48.31%in the unoxidized state to the lowest value of 29.57%in the case of linoleic acid 10 mmol/L,while theβ-sheet content gradually increased from 14.75%to 22.14%.Theβ-turn content also increased from 16.28%to 21.88%with the increase of oxidation degree,and the content of random coil generally showed an increasing trend.As the degree of oxidation increased,the hydrophobic interaction of the MP gel firstly increased and then decreased,reaching a maximum at 2 mmol/L,while the G'value(>68℃)reached a maximum at 2 mmol/L,which showed that the change of hydrophobic interaction was closely related to the change of protein secondary structure in MP gel.