南瓜种子萌发时贮藏蛋白及其酶活力的动态变化

Dynamic Changes of Storage Protein and Protease Activities During Germination of Pumpkin Seeds

[目的]研究南瓜种子萌发8 d内的蛋白质含量和蛋白酶活力的变化,阐明其种子萌发机理。[方法]采用Brad-ford法测定南瓜种子萌发过程中的可溶性蛋白含量的变化,以酪蛋白、BAPNA及ATEE为底物测定了蛋白酶活力的变化。[结果]南瓜种子从萌发到第8天,蛋白质含量下降68.1%,尤其在第2～3天时含量急剧下降。萌芽3 d的子叶制备的粗酶液中的酪蛋白酶活力最高;粗酶液可催化水解BAPNA,而对ATEE无明显水解;胰蛋白酶活力在萌芽期总体呈现下降趋势。[结论]种子萌发时贮藏物质代谢过程中的酶起着关键作用。

[Objective]The study aimed to research the change of the protein content and protease activities during germination of pumpkin seeds within 8 d and illustrate the seed germination mechanism.[Method]The change of soluble protein content during the germination of pumpkin seeds were measured by using Brad-ford method.The change of protease activities were measured with the casein,BAPNA and ATEE as substrates.[Result]The protein content in the pumpkin seeds was decreased by 68.1%from 0th to 8th d during the germination, especially with a rapid decreasing at 2th -3th d.The casein enzymatic activities in the crude enzyme liquid prepared with cotyledon after germination for 3 d was highest.The crude enzyme could catalyze and hydrolyze BAPNA,but it had no obvious hydrolysis on ATEE;The trypsin activities showed the downtrend in the germination stage in total.[Conclusion]When the seed was germinated,the enzyme produced during the metabolism process of stored substance played the key effect.