IUBMB Enzyme Nomenclature


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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