2 TROPINONE REDUCING ENZYMES FROM DATURA-STRAMONIUM TRANSFORMED ROOT CULTURES

Two different tropinone reductases (TR) were isolated from transformed root cultures of Datura stramonium. Both activities were completely separated by hydrophobic interaction chromatography and affinity chromatography. Gas chromatographic analysis of the reaction products showed one enzyme activity forming tropine only (TR I) and the other forming exclusively pseudotropine (TR II). TR I after extraction and purification showed about five-fold activity of TR II. Characterization of both enzymes revealed differences to tropinone reductases isolated previously from Datura stramonium, D. innoxia and Hyoscyamus niger, and differences between the individual enzyme proteins. TR I showed a pronounced pH-dependency while TR II was more tolerant to different pH-values. Both reductases accepted only NADPH as coenzyme; K(m) values were 1.39 mM (TR I) and 0.22 mM (TR II) for tropinone and 59-mu-M (TR I) and 17-mu-M (TR II) for NADPH.