冻藏对面筋蛋白二级结构的影响

采用圆二色谱法表征了不同冻藏模式和冻藏时间对小麦面筋蛋白二级结构的影响.结果表明:在SDS溶液中,未经冻藏的面筋蛋白二级结构主要由β折叠和无规则卷曲组成;当冻藏时间小于60天时,两种冻藏模式对小麦面筋蛋白的二级结构影响不大;恒温冻藏模式中面筋蛋白二级结构在冻藏90天时变化最显著,易溶部分中α螺旋转化为β折叠和β转角,难溶部分中β折叠和β转角转化为α螺旋和无规则卷曲;冻融冻藏模式中面筋蛋白二级结构在冻藏60天时变化最显著,易溶部分中α螺旋转化为β折叠和无规则卷曲,难溶部分中β折叠和β转角转化为α螺旋和无规则卷曲.这说明,在恒温冻藏模式下,只有当冻藏时间达到或超过90天的时候,才对面筋蛋白的二级结构产生影响,而在冻融模式下,冻藏时间仅为60天时便可对面筋蛋白的二级结构产生影响.

Effect of Frozen Storage on Secondary Structure of Gluten Proteins

This paper deals with the influences of frozen mode and frozen time on the secondary structure of wheat gluten proteins by means of circular dichroism spectroscopy.The results show that the secondary structure of the non-frozen gluten proteins in SDS solution is mainly composed of β sheets and random coils,that the two adopted frozen storage modes have no obvious effect on the secondary structure of the gluten proteins when the frozen time is less than 60 d,and that,in the thermostatic frozen storage mode,the secondary structure obviously changes after a storage for 90 d,the α helixes of the soluble gluten proteins turn into β sheets and β turns,and the β sheets and the β turns of the insoluble gluten proteins turn into α helixes and random coils.However,in the freeze-thaw storage mode,the secondary structure significantly changes after a storage for 60 d,the α helixes of the soluble gluten proteins turn into β sheets and random coils,and the β sheets and the β turns of the insoluble gluten proteins turn into α helixes and random coils.Thus,it is concluded that,in the thermostatic frozen storage mode,the secondary structure of the gluten proteins changes only when the frozen time is equal to or greater than 90 d,while in the freeze-thaw storage mode,the storage only for 60 d may affect the secondary structure.