Tropinone reductase II

In enzymology, a tropinone reductase II (EC 1.1.1.236) is an enzyme that catalyzes the chemical reaction

pseudotropine + NADP⁺ tropinone + NADPH + H⁺

Thus, the two substrates of this enzyme are pseudotropine 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 pseudotropine:NADP+ 3-oxidoreductase. Other names in common use include tropinone (psi-tropine-forming) reductase, pseudotropine forming tropinone reductase, tropinone reductase (ambiguous), and TR-II. This enzyme participates in alkaloid biosynthesis ii.

Structural studies

As of late 2007, 6 structures have been solved for this class of enzymes, with PDB accession codes 1AE1, 1IPE, 1IPF, 1XHL, 2AE1, and 2AE2.

References

• Drager B, Hashimoto T and Yamada Y (1988). "Purification and characterization of pseudotropine forming tropinone reductase from Hyoscyamus niger root cultures". Agric. Biol. Chem. 52 (10): 2663–2667. doi:10.1271/bbb1961.52.2663. 
• Couladis MM, Friesen JB, Landgrebe ME and Leete E (1991). "Enzymes catalysing the reduction of tropinone to tropine and ψ-tropine isolated from the roots of Datura innoxia". Pytochemistry 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. doi:10.1073/pnas.90.20.9591. PMC 47615. PMID 8415746. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=47615. 
• 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.