Purification and Characterization of Pseudotropine Forming Tropinone Reductase from Hyoscyamus niger Root Cultures

Abstract

A pseudotropine-forming tropinone reductase was extracted from root cultures of Hyoscyamus niger that produce the tropane alkaloids hyoscyamine and scopolamine. The enzyme stereospecifically reduces tropinone to pseudotropine, oxidizing NADPH. It has an approximate molecular weight of 84, 000 and a pH optimum between 5.8 and 6.25. The Km value for tropinone is 35.1 μmol/l and for NADPH 21.1 μmol/l. Substrate specificity was tested for NADPH and several tropinone analogues.