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 IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

:cis-3,4- leucopelargonidin + NADP⁺

\rightleftharpoons

(+)- dihydrokaempferol + NADPH + 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 serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Produ ...

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 u ...

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 semitrivial ...

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

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

s, 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 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, 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. Blue roses are often used to symbolize mystery or attaining the impossible. However, beca ...

, 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 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 ...

or coniferyl aldehyde or coumaraldehyde and NADPH 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 are ...

or coniferyl alcohol 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