The Enzyme Database

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Accepted name: tropinone reductase I
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 [1]. This enzyme along with EC, tropinone reductase II, represents a branch point in tropane alkaloid metabolism [4]. Tropine (the product of EC is incorporated into hyoscyamine and scopolamine whereas pseudotropine (the product of EC is the first specific metabolite on the pathway to the calystegines [4]. Both enzymes are always found together in any given tropane-alkaloid-producing species, have a common substrate, tropinone, and are strictly stereospecific [3].
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]
[EC created 1984, modified 2007]

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