【作者】 徐杏连；

【导师】 姜微波；

【作者基本信息】 中国农业大学 ， 农产品加工及贮藏工程， 2004， 硕士

【摘要】 蛋白酶在植物的生长发育、衰老和环境胁迫等生理过程中都起到重要的调控作用。植物衰老过程中蛋白酶合成量的增加及其活性的上升是导致蛋白质降解速率加快的主要原因。本实验通过对青口小白菜、京绿乌塌菜、京绿2号小油菜、大肉芥菜四种叶菜和两种食用嫩茎叶的泰国柳叶空心菜和小叶筒蒿进行采后蛋白降解及蛋白酶活性分析，并研究了不同前处理温度、不同反应温度、不同pH对衰老过程中蛋白酶的活性影响，同时分析了赤霉素和乙烯对上述叶菜衰老的影响。 采用考马斯亮监G-250及改进的SDS-Gelalin-PAGE方法，发现采收后的各种叶片可溶性蛋白均呈逐渐下降趋势，GA₃处理能显著延缓各种叶菜可溶性蛋白含量的下降；乙烯对叶片蛋白降解有促进作用；但是蛋白酶活性电泳显示只有小白菜叶片蛋白酶活性随着衰老进程而活性不断上升；小油菜、空心菜和筒蒿的蛋白酶活性一直保持较高水平而没有明显上升趋势；芥菜和乌塌菜叶片蛋白酶的明胶水解活性呈下降趋势。 实验同时还检测了各种实验叶菜的游离氨基酸含量、过氧化物酶活性和多酚氧化酶活性，发现小白菜、空心菜、筒蒿叶片中游离氨基酸含量先上升后下降，而乌塌菜、小油菜和芥菜叶片氨基酸含量呈逐渐下降趋势。GA₃处理能显著延缓小白菜、乌塌菜和小油菜游离氨基酸含量的下降，乙烯处理则显著促进除小白菜外的各种叶片游离氨基酸含量的下降。各种蔬菜采后过氧化物酶活性迅速上升，而多酚氧化酶活性在小白菜、乌塌菜和筒蒿叶片中呈快速下降趋势，在其它的叶片和嫩茎或叶柄中呈先上升后下降趋势。更多还原

【Abstract】 Intracelluar proteases play an important role in the growth, development, senescence and adaptation to environment stress. The enhancement of protease synthesis and increase of their activity have been considered to be responsible for protein degradation during senescence in plants. This study has been focused on the identification and characterization of proteases and degradation of protein related to senescence of leafy greenstuffs during senescence, with pak choi (Brassica. Chinensis), flat cabbage (Brassica. Campestris ssp. Chinensis van rosulari), yubaicai pak choi (Brassica campestris L ssp chinensis L), leaf mustard (Brassica juncea van foliosa), water spinach (Ipomoea aquatica. Forsk) and garland chrysanthemum (Chrysanthemum Coronarium.) used as models. The effects of sample pre-treatment temperature, incubation temperature and pH of the incubation buffer on the activities of proteases were also investigated. And senescence of different leaves regulated by applying gibberellic acid (GA3) or ethylene during storage was investigated too.By modified SDS-gelatin-PAGE assay, we found that the soluble protein contents were declined in all vegetables investigated during senescence. In fact, the declines were significantly retarded by the treatment of GA3 while promoted by the treatment of ethylene. Protease activity increased in parallel with the development of senescence only in the pak choi leaves, but not in yubaicai pak choi, water spinach and garland chrysanthemum leaves. However, there was a surprising decreased trend of proteases in flat cabbage and the leaf mustard leaves during senescence.The contents of free amino acids were measured and found to be decreased in leaves treated by ethylene during storage. The activities of peroxidase (POD) and polyphenol oxidase (PPO) of these materials were measured during storage. POD activities were increased in all leaves. PPO activities were increased at first but then decreased in the leaves, petioles and stems of all vegetables studied except the leaves of pak choi, flat cabbage and the garland chrysanthemum.更多还原