enzymology An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

, a dihydrokaempferol 4-reductase () is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

that

catalyzes Catalysis () is the increase in rate of a chemical reaction due to an added substance known as a catalyst (). Catalysts are not consumed by the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recycles quick ...

the

chemical reaction A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...

: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 Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require N ...

+ H⁺ Thus, the two substrates of this enzyme are cis-3,4-leucopelargonidin and NADP⁺, whereas its 3

products Product may refer to: Business * Product (business), an item that can be offered to a market to satisfy the desire or need of a customer. * Product (project management), a deliverable or set of deliverables that contribute to a business solution ...

are (+)-dihydrokaempferol,

, 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 ut ...

s, specifically those acting on the CH-OH group of donor with NAD⁺ or NADP⁺ as acceptor. The

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

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 ca ...

Function

Anthocyanidin Anthocyanidins are common plant pigments, the aglycones of anthocyanins. They are based on the flavylium cation, an oxonium ion, with various groups substituent, substituted for its hydrogen atoms. They generally change color from red through p ...

s, 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 ''Nepenthes burbidgea ...

s. DFR uses dihydromyricetin (

ampelopsin Ampelopsin, also known as dihydromyricetin and DHM, when used as an herbal medicine, is a flavanonol, a type of flavonoid. It is extracted from the Japanese raisin tree and found in '' Ampelopsis'' species ''japonica'', ''megalophylla'', and ''g ...

) 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 In genetics, complementary DNA (cDNA) is DNA that was reverse transcribed (via reverse transcriptase) from an RNA (e.g., messenger RNA or microRNA). cDNA exists in both single-stranded and double-stranded forms and in both natural and engin ...

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 toug ...

''. Researchers in Japan have genetically manipulated roses by using

RNA interference RNA interference (RNAi) is a biological process in which RNA molecules are involved in sequence-specific suppression of gene expression by double-stranded RNA, through translational or transcriptional repression. Historically, RNAi was known by ...

to knock out endogenous DFR, adding a gene DFR from an iris, and adding a gene for the blue pigment,

delphinidin Delphinidin (also delphinidine) is an anthocyanidin, a primary plant pigment, and also an antioxidant. Delphinidin gives blue hues to flowers in the genera ''Viola'' and ''Delphinium''. It also gives the blue-red color of the grape variety Cab ...

, in an effort to create a

blue rose A blue rose is a flower of the genus ''Rosa'' (family Rosaceae) that presents blue-to-violet pigmentation instead of the more common red, white, or yellow, through use of artificial means such as dyes. Blue roses are often used to symbolize myst ...

, 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 Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidit ...

biosynthesis pathway. In ''

Arabidopsis thaliana ''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small plant from the mustard family (Brassicaceae), native to Eurasia and Africa. Commonly found along the shoulders of roads and in disturbed land, it is generally ...

'', the enzyme uses

sinapaldehyde Sinapaldehyde is an organic compound with the formula HO(CH3O)2C6H2CH=CHCHO. It is a derivative of cinnamaldehyde, featuring one hydroxy group and two methoxy groups as substituents. It is an intermediate in the formation of sinapyl alcohol, a l ...

coniferyl aldehyde Coniferyl aldehyde is an organic compound with the formula HO(CH3O)C6H3CH=CHCHO. It is a derivative of cinnamaldehyde, featuring 4-hydroxy and 3-methoxy substituents. It is a major precursor to lignin. Biosynthetic role In sweetgum (''Liquidamba ...

or coumaraldehyde and

to produce

sinapyl alcohol Sinapyl alcohol is an organic compound structurally related to cinnamic acid. It is biosynthetized via the phenylpropanoid biochemical pathway, its immediate precursor being sinapaldehyde. This phytochemical is one of the monolignols, which a ...

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 compound ...

or coumaryl alcohol respectively and NADP⁺.

Structural studies

As of late 2007, two

structures A structure is an arrangement and organization of interrelated elements in a material object or system, or the object or system so organized. Material structures include man-made objects such as buildings and machines and natural objects such as ...

have been solved for this class of enzymes, with PDB accession codes and .

Function

Structural studies

References

Further reading