甜菊叶片细胞UDPG PPLase基本特征及电镜细胞化学定位

Studies on the Basic Characteristics and SubcellularLocalization of UDPG PPLase in the Leaves cellof Stevia rebaudiana Bertoni

经硫酸铵分级、DEAE-纤维素和葡聚糖凝胶柱层析,叶中UDPG PPLase被纯化166倍,该酶最适反应温度32℃,最佳反应pH8.0.2mmol/L的Ca^(2+)和5mmol/L的Mg^(2+)对该酶有较好激活效果,但无绝对依赖关系,Pb^(2+)对该酶有较强抑制作用,亚细胞分级分离结果表明95％的UDPG PPLase活性分布于46000×980cm /s^2上清液;电镜细胞化学定位研究表明,该酶主要定位于液泡、高尔基扁平囊和高尔基小泡;还讨论该酶在甜菊糖甙生物合成中的作用。

By means of ammonium sulfate fraction, and column chromatography on DEAE-Cellulose and Sephadex, UDPG PPLase was purified 166 folds. The optimal tempera-ture for the reaction of the enzyme was 32℃, the optimal pH was 8. 0. 2m mol/l Ca2+ and 5 mmol/1 Mg2+ was a good activative element for UDPG PPLase, but not an absolutely needed condition. Pb2+ showed strong inhibition. The result of subcellular fraction indicated that 95% of UDPG PPLase activity was distributed in the superatant of 46 000×980 cm/s2. The observation of electron microscopic cytochemistry demonstrated that UDPG PPLase was largely located in the vaeuloes, golgi body and golgi vesides. The role of UDPG PPLase in cell steviol-gtacosides biosythesis was also discussed.