In enzymology, a tropinone reductase I (EC 1.1.1.206) is an enzyme that catalyzes the chemical reaction

tropine + NADP⁺ ${\displaystyle \rightleftharpoons }$ tropinone + NADPH + H⁺

Thus, the two substrates of this enzyme are tropine and NADP⁺, whereas its 3 products are tropinone, NADPH, and H⁺.

This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The systematic name of this enzyme class is tropine:NADP⁺ 3alpha-oxidoreductase. Other names in common use include tropine dehydrogenase, tropinone reductase (ambiguous), and TR-I. This enzyme participates in alkaloid biosynthesis ii.

References

• Koelen KJ; Gross, GG (1982). "Partial purification and properties of tropine dehydrogenase from root cultures of Datura stramonium". Planta Med. 44 (4): 227–230. doi:10.1055/s-2007-971454. PMID 17402126.
• Couladis MM, Friesen JB, Landgrebe ME, Leete E (1991). "Enzymes catalysing the reduction of tropinone to tropine and ψ-tropine isolated from the roots of Datura innoxia'". Phytochemistry. 30 (3): 801–805. doi:10.1016/0031-9422(91)85255-X.
• Nakajima K, Hashimoto T, Yamada Y (1993). "Two tropinone reductases with different stereospecificities are short-chain dehydrogenases evolved from a common ancestor". Proc. Natl. Acad. Sci. U.S.A. 90 (20): 9591–5. Bibcode:1993PNAS...90.9591N. doi:10.1073/pnas.90.20.9591. PMC 47615. PMID 8415746.
• Drager B (2006). "Tropinone reductases, enzymes at the branch point of tropane alkaloid metabolism". Phytochemistry. 67 (4): 327–37. doi:10.1016/j.phytochem.2005.12.001. PMID 16426652.