Amine dehydrogenase
Encyclopedia
Amine Dehydrogenase also known as methylamine dehydrogenase (MADH), is a tryptophan tryptophylquinone
-dependent (TTQ-dependent) enzyme
that catalyzes
the oxidative deamination
of a primary amine to an aldehyde
and ammonia
. The reaction occurs as follows:
RCH2NH2 + H2O + acceptor
→ RCHO + NH3
+ reduced
acceptor
Amine dehydrogenase possesses an α2β2 structure with each smaller β subunit possessing a TTQ protein cofactor
.
Amine dehydrogenase, studied in Paracoccus denitrificans
, at least transiently forms a ternary complex to catalyze methylamine-dependent cytochrome c-551i reduction. Within this complex, electrons are transferred from the TTQ cofactor of MADH to the Type 1 copper center of amicyanin, and then to the heme
of the cytochrome
.
Tryptophan tryptophylquinone
Tryptophan tryptophylquinone is a molecule required for the functioning of amine dehydrogenase....
-dependent (TTQ-dependent) 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 oxidative deamination
Oxidative deamination
Oxidative deamination is a form of deamination that generates oxoacids in the liver.The presence of nitrous acid can cause transition mutations, by converting cytosine to uracil. Primarily occurs in the liver and kidneys.-In Urea cycle:...
of a primary amine to an aldehyde
Aldehyde
An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....
and ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
. The reaction occurs as follows:
RCH2NH2 + H2O + acceptor
Electron acceptor
An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. It is an oxidizing agent that, by virtue of its accepting electrons, is itself reduced in the process....
→ RCHO + NH3
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
+ reduced
Redox
Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....
acceptor
Amine dehydrogenase possesses an α2β2 structure with each smaller β subunit possessing a TTQ protein cofactor
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound that is bound to a protein and is required for the protein's biological activity. These proteins are commonly enzymes, and cofactors can be considered "helper molecules" that assist in biochemical transformations....
.
Amine dehydrogenase, studied in Paracoccus denitrificans
Paracoccus denitrificans
Paracoccus denitrificans, is a coccoid bacterium known for its nitrate reducing properties, its ability to replicate under conditions of hypergravity and for being the possible ancestor of the eukaryotic mitochondrion .-Description:...
, at least transiently forms a ternary complex to catalyze methylamine-dependent cytochrome c-551i reduction. Within this complex, electrons are transferred from the TTQ cofactor of MADH to the Type 1 copper center of amicyanin, and then to the heme
Heme
A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. Not all porphyrins contain iron, but a substantial fraction of porphyrin-containing metalloproteins have heme as their prosthetic group; these are...
of the cytochrome
Cytochrome
Cytochromes are, in general, membrane-bound hemoproteins that contain heme groups and carry out electron transport.They are found either as monomeric proteins or as subunits of bigger enzymatic complexes that catalyze redox reactions....
.