丝瓜果实发育过程中4—CL连接酶的特性研究

Study on Properties of 4-CL Ligase during the Fruits Development of Luffa Cylindrica Roem

以丝瓜（Spongegourd）果实为材料，分析了4-香豆酸辅酶A连接酶（4-CL）的理化性质及其在木质素合成和导管分子（TE）分化中作用。发现4－CL存在两种同工酶，经柱层析后，酶Ⅰ纯化15．68倍，含量为22．63％；酶Ⅱ纯化44．23倍，含量为3.91％。酶Ⅰ对得豆酸和咖啡酸有较大亲和性，对阿魏酸较小；而酶Ⅱ对香豆酸和咖啡酸有一定亲和性，对阿魏酸亲和性极小。酶Ⅰ有较好的热稳定性，最适温度为40℃，最适pH8.0.发现4－CL活性与木质素合成和TE分化有正相关性，表明4－CL是TE分化的标志酶，4－CL的热稳定性有利于丝瓜果实在8－9月份高温季节迅速成熟并木质化。

The 4-CL was purified roughly from the fruits of Sponge Gourd by ion-exchangechromatography on DEAE-Cellulose 52 column and its essential properties were characterized.The results showed that the 4-CL contained two isoenzymes, i.c. enzyme Ⅰ and enzymeⅡ. Ina single column chromatography step, a 15,68-fold purification of enzyme Ⅰ and 44.23-foldpurification of enzyme Ⅱ was observed. The purity of enzyme was 22.66 percent in the case ofenzymeⅠand 3.91 percent in the case of enzyme Ⅱ. The affinity of enzyme Ⅰ to 4-coumarateand coffee acid was higher than that of enzyme Ⅱ. And enzyme Ⅰto trans-ferulic acid wasmoderate, but to enzyme Ⅱ was very wek. Enzyme Ⅰ was still stable at 30-40℃ and at ph7.5-8.5. The optimal temperature was 40℃ and the pH-optimum was 8.0. The study of TEdiffecrentiation revealed that the activity of 4-CL was related much with the lignin biosynthsisand the TE differentiation, and there was a sequenlial relation among them. These results indicated that 4-CL could be a marker enzyme of TE differentiation, and its thermostabilityguaranted the fruits of Sponge Gould rapidly maturing in hightemperature season from Augustto September.