Reaction: tropine + NADP+ = tropinone + NADPH + H+
For diagram of reaction, click here
Glossary: tropine = 3α-hydroxytropane = tropan-3-endo-ol
Other name(s): tropine dehydrogenase; tropinone reductase (ambiguous); TR-I
Systematic name: tropine:NADP+ 3α-oxidoreductase
Comments: Also oxidizes other tropan-3α-ols, but not the corresponding β-derivatives . This enzyme along with EC 188.8.131.52, tropinone reductase II, represents a branch point in tropane alkaloid metabolism . Tropine (the product of EC 184.108.40.206) is incorporated into hyoscyamine and scopolamine whereas pseudotropine (the product of EC 220.127.116.11) is the first specific metabolite on the pathway to the calystegines . Both enzymes are always found together in any given tropane-alkaloid-producing species, have a common substrate, tropinone, and are strictly stereospecific .
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 118390-87-7
1. Koelen, K.J. and Gross, G.G. Partial purification and properties of tropine dehydrogenase from root cultures of Datura stramonium. Planta Med. 44 (1982) 227-230.
2. Couladis, M.M, Friesen, J.B., Landgrebe, M.E. and Leete, E. Enzymes catalysing the reduction of tropinone to tropine and ψ-tropine isolated from the roots of Datura innoxia. Pytochemistry 30 (1991) 801-805.
3. Nakajima, K., Hashimoto, T. and Yamada, Y. Two tropinone reductases with different stereospecificities are short-chain dehydrogenases evolved from a common ancestor. Proc. Natl. Acad. Sci. USA 90 (1993) 9591-9595. [PMID: 8415746]
4. Dräger, B. Tropinone reductases, enzymes at the branch point of tropane alkaloid metabolism. Phytochemistry 67 (2006) 327-337. [PMID: 16426652]