In enzymology, a dihydrokaempferol 4-reductase is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that catalyzes

Catalysis

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 the chemical reaction

Chemical reaction

A chemical reaction is a process that leads to the transformation of one set of chemical substances to another. Chemical reactions can be either spontaneous, requiring no input of energy, or non-spontaneous, typically following the input of some type of energy, such as heat, light or electricity...

cis-3,4-leucopelargonidin

Leucopelargonidin

Leucopelargonidin is a colorless chemical compound related to leucoanthocyanins. It can be found in Albizia lebbeck , in the fruit of Anacardium occidentale , in the fruit of Areca catechu , in the fruit of Hydnocarpus wightiana , in the rhizome of Rumex hymenosepalus , in Zea Mays and...

 + NADP⁺

Nicotinamide adenine dinucleotide phosphate

Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or TPN in older notation , is a coenzyme used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent....

  (+)-dihydrokaempferol + NADPH

Nicotinamide adenine dinucleotide phosphate

Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or TPN in older notation , is a coenzyme used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent....

 + H⁺

Thus, the two substrates

Substrate (biochemistry)

In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate. In the case of a single substrate, the substrate binds with the enzyme active site, and an enzyme-substrate complex is formed. The substrate is transformed into one or...

 of this enzyme are cis-3,4-leucopelargonidin and NADP⁺

Nicotinamide adenine dinucleotide phosphate

Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or TPN in older notation , is a coenzyme used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent....

, whereas its 3 products

Product (chemistry)

Product are formed during chemical reactions as reagents are consumed. Products have lower energy than the reagents and are produced during the reaction according to the second law of thermodynamics. The released energy comes from changes in chemical bonds between atoms in reagent molecules and...

 are (+)-dihydrokaempferol, NADPH

Nicotinamide adenine dinucleotide phosphate

Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or TPN in older notation , is a coenzyme used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent....

, and H⁺

Hydrogen ion

Hydrogen ion is recommended by IUPAC as a general term for all ions of hydrogen and its isotopes.Depending on the charge of the ion, two different classes can be distinguished: positively charged ions and negatively charged ions....

.

This enzyme belongs to the family of oxidoreductase

Oxidoreductase

In biochemistry, an oxidoreductase is an enzyme that catalyzes the transfer of electrons from one molecule to another...

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

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 called chalcones, which contain two phenyl rings...

.

Function

Dihydroflavonol 4-reductase is an enzyme part of the lignin

Lignin

Lignin or lignen is a complex chemical compound most commonly derived from wood, and an integral part of the secondary cell walls of plants and some algae. The term was introduced in 1819 by de Candolle and is derived from the Latin word lignum, meaning wood...

 biosynthesis pathway.

Anthocyanidin

Anthocyanidin

Anthocyanidins are common plant pigments. They are the sugar-free counterparts of anthocyanins based on the flavylium ion or 2-phenylchromenylium, which is a type of oxonium ion . They form a large group of polymethine dye. In particular anthocyanidins are salt derivatives of the...

s are further reduced by the enzyme dihydroflavonol 4-reductase to the corresponding colorless leucoanthocyanidin

Leucoanthocyanidin

Leucoanthocyanidin are colorless chemical compounds related to anthocyanidins and anthocyanins. Leucoanthocyanins can be found in Anadenanthera peregrina and in several species of Nepenthes including Nepenthes rajah, Nepenthes burbidgeae, Nepenthes tentaculata, Nepenthes × alisaputrana and...

s.

Dihydroflavonol 4-reductase uses dihydromyricetin (ampelopsin

Ampelopsin

Ampelopsin is a flavanonol, a type of flavonoid. It can be found in the Japanese Raisin Tree Hovenia dulcis. The compound is credited with hepatoprotective effects....

) NADPH and 2 H⁺ to produce leucodelphinidin

Leucodelphinidin

Leucodelphinidin is a colorless chemical compound related to leucoanthocyanidins. It can be found in Acacia auriculiformis, in the bark of Karada and in the kino from Eucalyptus pilularis....

 and NADP.

In Arabidopsis thaliana

Arabidopsis thaliana

Arabidopsis thaliana is a small flowering plant native to Europe, Asia, and northwestern Africa. A spring annual with a relatively short life cycle, arabidopsis is popular as a model organism in plant biology and genetics...

, the enzyme uses sinapaldehyde

Sinapaldehyde

Sinapaldehyde is a chemical compound found in Senra incana .In Arabidopsis thaliana, this compound is part of the lignin biosynthesis pathway. The enzyme dihydroflavonol 4-reductase uses sinapaldehyde and NADPH to produce sinapyl alcohol and NADP+.It is a low molecular weight phenolic compound...

 or coniferyl aldehyde

Coniferyl aldehyde

Coniferyl aldehyde is a low molecular weight phenolic compound susceptible to be extracted from cork stoppers into wine.-Metabolism:Coniferyl-alcohol dehydrogenase uses coniferyl alcohol and NADP+ to produce coniferyl aldehyde, NADPH, and H+....

 or coumaraldehyde and NADPH

Nicotinamide adenine dinucleotide phosphate

Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or TPN in older notation , is a coenzyme used in anabolic reactions, such as lipid and nucleic acid synthesis, which require NADPH as a reducing agent....

 to produce sinapyl alcohol

Sinapyl alcohol

Sinapyl alcohol is an organic compound derived from cinnamic acid. This phytochemical is one of the monolignols. It is biosynthetized via the phenylpropanoid biochemical pathway, its immediate precursor being sinapaldehyde. Sinapyl alcohol is a precursor to lignin or lignans. It is also a...

 or coniferyl alcohol

Coniferyl alcohol

Coniferyl alcohol is an organic compound. This colourless crystalline solid is a phytochemical, one of the monolignols. It is synthethized via the phenylpropanoid biochemical pathway. When copolymerized with related aromatic compounds, coniferyl alcohol forms lignin or lignans...

 or coumaryl alcohol respectively and NADP⁺.

Structural studies

As of late 2007, two structures

Tertiary structure

In biochemistry and molecular biology, the tertiary structure of a protein or any other macromolecule is its three-dimensional structure, as defined by the atomic coordinates.-Relationship to primary structure:...

 have been solved for this class of enzymes, with PDB

Protein Data Bank

The Protein Data Bank is a repository for the 3-D structural data of large biological molecules, such as proteins and nucleic acids....

accession codes and .