Azobenzene reductase also known as azoreductase () 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 ...

: :N,N-dimethyl-1,4-phenylenediamine + aniline + NADP⁺

\rightleftharpoons

4-(dimethylamino)azobenzene + NADPH + H⁺ The 3 substrates of this enzyme are N,N-dimethyl- 1,4-phenylenediamine,

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...

, and

nicotinamide adenine dinucleotide phosphate 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 NAD ...

ion, 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 4-(dimethylamino)

azobenzene Azobenzene is a photoswitchable chemical compound composed of two phenyl rings linked by a N=N double bond. It is the simplest example of an aryl azo compound. The term 'azobenzene' or simply 'azo' is often used to refer to a wide class of simi ...

, and

hydrogen ion A hydrogen ion is created when a hydrogen atom loses or gains an electron. A positively charged hydrogen ion (or proton) can readily combine with other particles and therefore is only seen isolated when it is in a gaseous state or a nearly particle ...

. 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 other nitrogenous compounds as donors with NAD+ or NADP+ as acceptor.

Mechanism

The reaction catalyzed by this enzyme proceeds via a ping-pong mechanism by using 2 equivalents of NAD(P)H to reduce one equivalent of the

azo compound Azo compounds are organic compounds bearing the functional group diazenyl (, in which R and R′ can be either aryl or alkyl groups). IUPAC defines azo compounds as: "Derivatives of diazene (diimide), , wherein both hydrogens are substituted ...

substrate (for example

methyl red Methyl red (2-(''N'',''N''-dimethyl-4-aminophenyl) azobenzenecarboxylic acid), also called C.I. Acid Red 2, is an indicator dye that turns red in acidic solutions. It is an azo dye, and is a dark red crystalline powder. Methyl red is a pH indica ...

where Ar = ''p''-

dimethylaniline ''N'',''N''-Dimethylaniline (DMA) is an organic chemical compound, a substituted derivative of aniline. It consists of a tertiary amine, featuring dimethylamino group attached to a phenyl group. This oily liquid is colourless when pure, but comm ...

and Ar' = ''o''-

benzoic acid Benzoic acid is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, ...

) into two equivalents of

product: : Ar–N=N–Ar' + 2(NAD(P)H + H⁺)

\rightleftharpoons

Ar–NH₂ + NH₂–Ar' + 2NAD(P)⁺

Substrate specificity

Most azoreductase isoenzymes can

reduce Reduction, reduced, or reduce may refer to: Science and technology Chemistry * Reduction (chemistry), part of a reduction-oxidation (redox) reaction in which atoms have their oxidation state changed. ** Organic redox reaction, a redox react ...

methyl red, but are not able to reduce sulfonated azo dyes. The unique azoreductase

isozyme In biochemistry, isozymes (also known as isoenzymes or more generally as multiple forms of enzymes) are enzymes that differ in amino acid sequence but catalyze the same chemical reaction. Isozymes usually have different kinetic parameters (e.g. dif ...

from ''

Bacillus ''Bacillus'' (Latin "stick") is a genus of Gram-positive, rod-shaped bacteria, a member of the phylum '' Bacillota'', with 266 named species. The term is also used to describe the shape (rod) of other so-shaped bacteria; and the plural ''Bacill ...

'' sp. B29 has the ability to reduce sulfonated azo dyes however.

Nomenclature

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 N,N-dimethyl-1,4-phenylenediamine, aniline:NADP+ oxidoreductase. Other names in common use include: * azo reductase, * azoreductase, * azo-dye reductase, * dibromopropylaminophenylazobenzoic azoreductase, * dimethylaminobenzene reductase, * methyl red azoreductase, * N,N-dimethyl-4-phenylazoaniline azoreductase, * NAD(P)H:1-(4'-sulfophenylazo)-2-naphthol oxidoreductase, * NADPH2-dependent azoreductase, * NADPH2:4-(dimethylamino)azobenzene oxidoreductase, * NC-reductase, * new coccinea (NC)-reductase, * nicotinamide adenine dinucleotide (phosphate) azoreductase, * orange I azoreductase, * orange II azoreductase, * p-aminoazobenzene reductase, and * p-dimethylaminoazobenzene azoreductase.

Structural studies

As of late 2007, 3

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 . Please check the last updated data o
RCSB PDB site

Mechanism

Substrate specificity

Nomenclature

Structural studies

References

Further reading