In
enzymology
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. A ...
, a taurine dioxygenase () is an
enzyme that
catalyzes
Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...
the
chemical reaction.
:taurine + 2-oxoglutarate + O
2 sulfite + aminoacetaldehyde + succinate + CO
2
The 3
substrates of this enzyme are
taurine,
2-oxoglutarate, and
O2, whereas its 4
products are
sulfite
Sulfites or sulphites are compounds that contain the sulfite ion (or the sulfate(IV) ion, from its correct systematic name), . The sulfite ion is the conjugate base of bisulfite. Although its acid ( sulfurous acid) is elusive, its salts are wide ...
,
aminoacetaldehyde,
succinate, and
CO2.
This enzyme belongs to the family of
oxidoreductases, specifically those acting on paired donors, with O2 as oxidant and incorporation or reduction of oxygen. The oxygen incorporated need not be derived from O2 with 2-oxoglutarate as one donor, and incorporation of one atom o oxygen into each donor. The
systematic name of this enzyme class is taurine, 2-oxoglutarate:O2 oxidoreductase (sulfite-forming). Other names in common use include 2-aminoethanesulfonate dioxygenase, and alpha-ketoglutarate-dependent taurine dioxygenase. This enzyme participates in
taurine and hypotaurine metabolism
Taurine (), or 2-aminoethanesulfonic acid, is an organic compound that is widely distributed in animal tissues. It is a major constituent of bile and can be found in the large intestine, and accounts for up to 0.1% of total human body weight. I ...
. It has 3
cofactors
Cofactor may also refer to:
* Cofactor (biochemistry), a substance that needs to be present in addition to an enzyme for a certain reaction to be catalysed
* A domain parameter in elliptic curve cryptography, defined as the ratio between the order ...
:
iron,
Ascorbate
Vitamin C (also known as ascorbic acid and ascorbate) is a water-soluble vitamin found in citrus and other fruits and vegetables, also sold as a dietary supplement and as a topical 'serum' ingredient to treat melasma (dark pigment spots) and ...
, and
Fe2+
In chemistry, the adjective Ferrous indicates a compound that contains iron(II), meaning iron in its +2 oxidation state, possibly as the divalent cation Fe2+. It is opposed to "ferric" or iron(III), meaning iron in its +3 oxidation state, such as ...
.
Structural studies
As of late 2007, 4
structures have been solved for this class of enzymes, with
PDB accession codes , , , and .
Mechanism
Initiating steps
In the decomposition of taurine, it has been shown that molecular oxygen is activated by Iron II, which lies in the coordinating complex of taurine dioxygenase. Here the enzyme with conjunction of an Iron II and 2-oxoglutarate maintain non-covalent bonds by electrostatic interactions, and coordinate a nucleophilic attack from dioxygen on 2-oxoglutarate carbon number 2.
This leads to the two oxidations, one on 2-oxoglutarate, and another on taurine, each one electron.
References
Further reading
*
EC 1.14.11
Iron enzymes
Ascorbate enzymes
Enzymes of known structure
{{1.14-enzyme-stub