In enzymology, a dihydrokaempferol 4-reductase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

that catalyzes the

chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...

:cis-3,4-

leucopelargonidin Leucopelargonidin is a colorless chemical compound related to leucoanthocyanins. It can be found in ''Albizia lebbeck'' (East Indian walnut), in the fruit of ''Anacardium occidentale'' (Cashew), in the fruit of ''Areca catechu'' (Areca nut), in th ...

+ NADP⁺

\rightleftharpoons

(+)-

dihydrokaempferol Aromadendrin (aromodendrin or dihydrokaempferol) is a flavanonol, a type of flavonoid. It can be found in the wood of ''Pinus sibirica''. Metabolism The enzyme dihydrokaempferol 4-reductase uses ''cis''-3,4-leucopelargonidin and NADP+ to prod ...

+ 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

oxidoreductase In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule, the reductant, also called the electron donor, to another, the oxidant, also called the electron acceptor. This group of enzymes usually ...

s, 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 Flavonoids are synthesized by the phenylpropanoid metabolic pathway in which the amino acid phenylalanine is used to produce 4-coumaroyl-CoA. This can be combined with malonyl-CoA to yield the true backbone of flavonoids, a group of compounds ...

Function

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

leucoanthocyanidin Leucoanthocyanidin (flavan-3,4-diols) are colorless chemical compounds related to anthocyanidins and anthocyanins. Leucoanthocyanins can be found in ''Anadenanthera peregrina'' and in several species of '' Nepenthes'' including '' N. burbidgea ...

s. DFR uses dihydromyricetin (

ampelopsin Ampelopsin, also known as dihydromyricetin and DHM, when purported as an effective ingredient in supplements and other tonics, is a flavanonol, a type of flavonoid. It is extracted from the Japanese raisin tree and found in ''Ampelopsis'' species ...

) NADPH and 2 H⁺ to produce

leucodelphinidin Leucodelphinidin is a colorless chemical compound related to leucoanthocyanidins. It can be found in ''Acacia auriculiformis'', in the bark of Karada ('' Cleistanthus collinus'') and in the kino (gum) from ''Eucalyptus pilularis''. Other species ...

and NADP. A cDNA for DFR has been cloned from the orchid ''

Bromheadia finlaysoniana ''Bromheadia finlaysoniana'', commonly known as the pale reed orchid and as ''Bromheadia pulchra'' in Australia, is a plant in the orchid family and is native to areas from Indochina to northern Australia. It is a terrestrial orchid with a tough ...

''. 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.Katsumoto Y et al (2007) Engineering of the Rose Flavonoid Biosynthetic Pathway Successfully Generated Blue-Hued Flowers Accumulating Delphinidin Plant Cell Physiol. 48(11): 1589–160

/ref>Phys.Org website. April 4, 200
Plant gene replacement results in the world's only blue rose
/ref> 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 Coniferyl alcohol is an organic compound with the formula HO(CH3O)C6H3CH=CHCH2OH. A colourless or white solid, it is one of the monolignols, produced via the phenylpropanoid biochemical pathway. When copolymerized with related aromatic compounds, ...

coumaryl alcohol Paracoumaryl alcohol is a phytochemical, one of the monolignols. It is a white solid. ''p''-Coumaryl alcohol is a major precursor to lignin or lignans. Biosynthesis and occurrence It is synthesized via the phenylpropanoid biochemical pathway. ...

respectively and NADP⁺.

Structural studies

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

Function

Structural studies

References

Further reading