Hashimoto T, Matsuda J, Yamada Y
Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto University, Japan.
FEBS Lett. 1993 Aug 23;329(1-2):35-9. doi: 10.1016/0014-5793(93)80187-y.
In several solanaceous plants, hyoscyamine is first hydroxylated at the 6 beta-position, and then epoxidized to scopolamine. We expressed hyoscyamine 6 beta-hydroxylase (H6H) in Escherichia coli as a fusion protein with maltose-binding protein. The crude cell extract from the bacterium that expressed the soluble fusion protein showed a strong hydroxylase activity and a weak epoxidase activity. When 100 microM of hyoscyamine was fed to the recombinant bacterium, the alkaloid was first converted to 6 beta-hydroxy hyoscyamine, and then to scopolamine, which was almost the only alkaloid found in the culture after one week. Therefore, H6H catalyzes two consecutive reactions that oxidize hyoscyamine to scopolamine.
在几种茄科植物中，莨菪碱首先在6β位被羟基化，然后环氧化为东莨菪碱。我们将莨菪碱6β-羟化酶（H6H）在大肠杆菌中表达为与麦芽糖结合蛋白的融合蛋白。表达可溶性融合蛋白的细菌的粗细胞提取物显示出很强的羟化酶活性和较弱的环氧化酶活性。当向重组细菌中加入100微摩尔的莨菪碱时，该生物碱首先转化为6β-羟基莨菪碱，然后转化为东莨菪碱，一周后东莨菪碱几乎是培养物中唯一发现的生物碱。因此，H6H催化两个连续反应，将莨菪碱氧化为东莨菪碱。
