KEGG   ENZYME: 1.1.1.236
Entry
EC 1.1.1.236                Enzyme                                 
Name
tropinone reductase II;
tropinone (psi-tropine-forming) reductase;
pseudotropine forming tropinone reductase;
tropinone reductase (ambiguous);
TR-II
Class
Oxidoreductases;
Acting on the CH-OH group of donors;
With NAD+ or NADP+ as acceptor
Sysname
pseudotropine:NADP+ 3-oxidoreductase
Reaction(IUBMB)
pseudotropine + NADP+ = tropinone + NADPH + H+ [RN:R06734]
Reaction(KEGG)
R06734
Substrate
pseudotropine [CPD:C02066];
NADP+ [CPD:C00006]
Product
tropinone [CPD:C00783];
NADPH [CPD:C00005];
H+ [CPD:C00080]
Comment
This enzyme along with EC 1.1.1.206, tropine dehydrogenase, represents a branch point in tropane alkaloid metabolism [3]. Tropine (the product of EC 1.1.1.206) is incorporated into hyoscyamine and scopolamine whereas pseudotropine (the product of EC 1.1.1.236) is the first specific metabolite on the pathway to the calystegines [3]. Both enzymes are always found together in any given tropane-alkaloid-producing species, have a common substrate, tropinone, and are strictly stereospecific [2].
History
EC 1.1.1.236 created 1992, modified 2007
Pathway
ec00960  Tropane, piperidine and pyridine alkaloid biosynthesis
ec01110  Biosynthesis of secondary metabolites
Orthology
K05354  tropinone reductase II
Genes
SLY101256174
SPEN107018368
SOT102589607(TRII)
CANN107872392
Reference
1
  Authors
Drager, B., Hashimoto, T. and Yamada, Y.
  Title
Purification and characterization of pseudotropine forming tropinone reductase from Hyoscyamus niger root cultures.
  Journal
Agric Biol Chem 52:2663-2667 (1988)
Reference
2
  Authors
Couladis, M.M, Friesen, J.B., Landgrebe, M.E. and Leete, E.
  Title
Enzymes catalysing the reduction of tropinone to tropine and psi-tropine isolated from the roots of Datura innoxia.
  Journal
Pytochemistry 30:801-805 (1991)
Reference
3  [PMID:8415746]
  Authors
Nakajima K, Hashimoto T, Yamada Y
  Title
Two tropinone reductases with different stereospecificities are short-chain dehydrogenases evolved from a common ancestor.
  Journal
Proc Natl Acad Sci U S A 90:9591-5 (1993)
DOI:10.1073/pnas.90.20.9591
  Sequence
Reference
4  [PMID:16426652]
  Authors
Drager B.
  Title
Tropinone reductases, enzymes at the branch point of tropane alkaloid metabolism.
  Journal
Phytochemistry 67:327-37 (2006)
DOI:10.1016/j.phytochem.2005.12.001
Other DBs
ExplorEnz - The Enzyme Database: 1.1.1.236
IUBMB Enzyme Nomenclature: 1.1.1.236
ExPASy - ENZYME nomenclature database: 1.1.1.236
BRENDA, the Enzyme Database: 1.1.1.236
CAS: 136111-61-0

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