桂花开放与衰老过程中花瓣蛋白酶活性与种类的变化

The Proteinase Activity and Types of Osmanthus fragrans Petals During Flower Opening and Senescence

以自然栽培条件下的桂花(Osmanthus fragrans)品种‘柳叶金桂’花瓣为试材,对其铃梗期、初花期、盛花期、盛花末期和萎蔫期的可溶性蛋白质和游离氨基酸含量及蛋白酶的活性和种类变化进行了检测。结果表明,伴随开花进程,花瓣可溶性蛋白质含量先增后减,游离氨基酸含量则持续上升;花瓣蛋白酶检测的最适温度为37℃,最适pH为8.0;分光光度计法及底物胶电泳法检测时均发现,桂花开花与衰老过程中,花瓣总蛋白酶活性持续上升,在盛花末期达到峰值,至萎蔫期迅速下降;利用专一性酶抑制剂检测到花瓣衰老过程中的丝氨酸蛋白酶、半胱氨酸蛋白酶和金属蛋白酶3种蛋白酶,其中丝氨酸蛋白酶活性最强,约占总活性的65%～75%,是影响桂花花瓣衰老最主要的蛋白酶。

The contents of soluble protein and free amino acid,the changes of proteinase activity and types of Osmanthus fragrans‘Liuye Jingui’were determined during flower opening and development stages from linggeng stage,initial flowering stage,full flowering stage,late full flowering stage to wilting stage. The results showed that variation patterns between soluble protein and free amino acid were different. The optimum temperature and pH for protease measure were 37 ℃ and pH 8.0 respectively. The petal proteinase activity which was detected by spectrophotometry and gel-SDS-PAGE electrophoresis increased continuously until late full flowering stage,and then sharply decreased at wilting stage. Three kinds of proteinases,serine protease,cystein protease and metallo protease,were found by using proteinase inhibitors. Serine protease,accounted for about 65%–75% in total,was the most active one among the three proteases to influence petal senescence of sweet osmanthus.