人参毛状根糖基转移酶的分离纯化及酶学性质研究

Purification and Characterization of Glucosyltransferase from Panax Ginseng Hairy Root Cultures

首次从人参毛状根中提取分离了糖基转移酶，用SDS-PAGE测定其相对分子质量为56．6k。该酶以对羟基苯甲酸为底物时的Km=0．399nmol／L，Vmax=2．74nmol／min，反应的最适温度为45℃，最适pH值为8．0。该酶在60℃以下，pH4．0～10．0范围内保持稳定。Na^＋，K^＋，Mg^2＋Ca^2＋，Zn^2＋，Ag^＋，Ba^2＋对酶活力有抑制作用，Fe^2＋和Cu^2＋对酶活力有一定的促进作用，而Mn^2＋和Co^2＋对酶活力没有影响。

To study the biotransformaion zymologic basis of the Panax ginseng hairy root cultures, the crude enzyme of glucosyltransferase from Panax ginseng hairy root cultures was made by the fractional precipitation of ammonium sulphate. After the procedure of Hiprep Q ion-exchange chromatography, a 56.6 k glucosyltransferase was isolated. The apparent Km value for p-hydroxybenzoic acid was 0. 399 nmol/L, and its Vmax value was 2. 74 nmol/min. Its activity was optimal in pH 8. 0 and at 45℃, and the enzyme was stable from pH 4.0 to pH 10. 0 under the condition of temperature below 60℃. In the ion study, the enzyme activity was slightly enhanced by Fe^2＋ and Cu^2＋ , but inhibited by Na^＋ , K^＋ , Mg^2＋ , Ca^2＋ , Zn^2＋ , Ag^＋ and Ba^2＋. Mn^2＋ and Co^2＋ had very slight effect on the activity of the glucosyltransferase. All the results were coincident with the provious glucosyltransferase research and this was the first report on the glucosyltransferase from the Panax ginseng hairy root cultures.