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Two‐step epoxidation of hyoscyamine to scopolamine is catalyzed by bifunctional hyoscyamine 6β‐hydroxylase
Author(s) -
Hashimoto Takashi,
Matsuda Jun,
Yamada Yasuyuki
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80187-y
Subject(s) - hyoscyamine , tropane , chemistry , scopolamine , alkaloid , escherichia coli , stereochemistry , biochemistry , biology , solanaceae , pharmacology , gene
In several solanaceous plants, hyoscyamine is first hydroxylated at the 6β‐position, and then epoxidized to scopolamine. We expressed hyoscyamine 6β‐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 μM of hyoscyamine was fed to the recombinant bacterium, the alkaloid was first converted to 6β‐hydroxyhyoscyamine, 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.