微波加热下表没食子儿茶素对海鲈鱼肌球蛋白氧化的影响

Effects of Epigallocatechin on Myosin of Sea Bass Oxidation Caused by Microwave Heating

为了研究微波加热下没食子儿茶素对海鲈鱼肌球蛋白氧化的影响,采用不同质量浓度(20,40μg/mL和60μg/mL)的表没食子儿茶素(EGC)处理海鲈鱼肌球蛋白,研究其对肌球蛋白的影响机制。EGC能够延缓微波处理后肌球蛋白羰基和二聚酪氨酸含量的升高和总巯基含量的降低;相对对照,羰基含量降低了19.82%~72.67%。添加EGC的肌球蛋白聚集体较少,且分布均匀。微波促使蛋白质分子去折叠致使荧光强度上升,EGC维持了蛋白质三级结构的相对稳定性,延缓荧光强度上升。微波前,添加低质量浓度(20,40μg/mL)EGC可显著增加α-螺旋含量,维持蛋白质二级结构的稳定性。微波加热后20μg/mL EGC维持了蛋白质二级结构的稳定性。分子动力学模拟结果表明,肌球蛋白与EGC复合物在升温电场下氨基酸残基均方根(RMSF)、均方根偏差(RMSD)、溶剂可及表面积(SASA)降低,氢键(HBOND)下降速率减慢,二级结构波动减少,提升了肌球蛋白的热稳定性。肌球蛋白通过与EGC之间产生氢键和疏水相互作用,提升了复合物在升温电场下的稳定性。

In order to study the effect of epigallocatechin on the oxidation of myosin in sea bass under microwave heating,differentmass concentrations of epigallocatechin(20,40μg/mL and 60μg/mL)were used to inhibit myosin oxidation and study the mechanism of its effect on myosin.EGC could delay the increase of carbonyl content and dityrosine of myosin and the decrease of total sulfhydryl content after microwave treatment.Carbonyl content was reduced by 19.82%-72.67%compared with the control.AFM showed that the myosin treated with EGC were small and evenly distributed.Microwave induced myosin to unfold and increased fluorescence intensity.EGC maintained the relative stability of the tertiary structures and delayed the increase of fluorescence intensity.Before microwave,low mass concentration EGC(20,40μg/mL)significantly increasedα-helix content and maintained the stability of myosin secondary structure.After microwave,20μg/mL EGC maintained the stability of secondary structure.Molecular dynamics simulation showed that RMSF and RMSD value of myosin-EGC decreased,SASA decreased,secondary structure fluctuation decreased.It was found that myosin enhanced the stability of the complex under heating electric field by hydrogen bonding and hydrophobic interaction with EGC.