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In enzymology, a dihydrokaempferol 4-reductase (EC 1.1.1.219) is an enzyme that catalyzes the chemical reaction

cis-3,4-leucopelargonidin + NADP ${\displaystyle \rightleftharpoons }$ (+)-dihydrokaempferol + NADPH + H

Thus, the two substrates of this enzyme are cis-3,4-leucopelargonidin and NADP, whereas its 3 products are (+)-dihydrokaempferol, 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 cis-3,4-leucopelargonidin:NADP 4-oxidoreductase. Other names in common use include dihydroflavanol 4-reductase (DFR), dihydromyricetin reductase, NADPH-dihydromyricetin reductase, and dihydroquercetin reductase. This enzyme participates in flavonoid biosynthesis.

Function

Anthocyanidins, common plant pigments, are further reduced by the enzyme dihydroflavonol 4-reductase (DFR) to the corresponding colorless leucoanthocyanidins.

DFR uses dihydromyricetin (ampelopsin) NADPH and 2 H to produce leucodelphinidin and NADP.

A cDNA for DFR has been cloned from the orchid Bromheadia finlaysoniana.

Researchers in Japan have genetically manipulated roses by using RNA interference to knock out endogenous DFR, adding a gene DFR from an iris, and adding a gene for the blue pigment, delphinidin, in an effort to create a blue rose, which is being sold worldwide.

Dihydroflavonol 4-reductase is an enzyme part of the lignin biosynthesis pathway. In Arabidopsis thaliana, the enzyme uses sinapaldehyde or coniferyl aldehyde or coumaraldehyde and NADPH to produce sinapyl alcohol or coniferyl alcohol or coumaryl alcohol respectively and NADP.

Structural studies

As of late 2007, two structures have been solved for this class of enzymes, with PDB accession codes 2C29 and 2IOD.

References

1. Nakajima J, Tanaka Y, Yamazaki M, Saito K (July 2001). "Reaction mechanism from leucoanthocyanidin to anthocyanidin 3-glucoside, a key reaction for coloring in anthocyanin biosynthesis". J. Biol. Chem. 276 (28): 25797–803. doi:10.1074/jbc.M100744200. PMID 11316805.
2. "Leucodelphinidin biosynthesis". MetaCyc. SRI International.
3. Les cibles d’amélioration pour la qualité des raisins: L’exemple des flavonoïdes, Nancy Terrier (French)
4. The isolation, molecular characterization and expression of dihydroflavonol 4-reductase cDNA in the orchid, Bromheadia finlaysoniana. Chye-Fong Liew, Chiang-Shiong Loh, Chong-Jin Goh and Saw-Hoon Lim, Plant Science, Volume 135, Issue 2, 10 July 1998, Pages 161–169, doi:10.1016/S0168-9452(98)00071-5
5. Katsumoto Y et al (2007) Engineering of the Rose Flavonoid Biosynthetic Pathway Successfully Generated Blue-Hued Flowers Accumulating Delphinidin Plant Cell Physiol. 48(11): 1589–1600
6. Phys.Org website. April 4, 2005 Plant gene replacement results in the world's only blue rose
7. "Dihydroflavonol 4-reductase". Arabidopsis Reactome. Archived from the original on 2016-01-30. Retrieved 2010-11-11.

Further reading

• Heller W, Forkmann G, Britsch L, Grisebach H (1985). "Enzymatic reduction of (+)-dihydroflavonols to flavan-3,4-cis- diols with flower extracts from Matthiola incana and its role in anthocyanin biosynthesis". Planta. 165 (2): 284–287. Bibcode:1985Plant.165..284H. doi:10.1007/BF00395052. PMID 24241054. S2CID 29590896.
• Stafford HA; Lester HH (1985). "Flavan-3-ol biosynthesis the conversion of (+)- dihydromyricetin to its flavan-3,4-diol (leucodelphinidin) and to (+)-gallocatechin by reductases extracted from tissue-cultures of Ginkgo biloba and Pseudotsuga-menziesii". Plant Physiol. 78 (4): 791–794. doi:10.1104/pp.78.4.791. PMC 1064823. PMID 16664326.

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