Coproporphyrinogen III oxidase
Encyclopedia
Coproporphyrinogen-III oxidase, mitochondrial is an enzyme
that in humans is encoded by the CPOX gene
. A genetic defect in the enzyme results in a reduced production of heme
in animals. The medical condition associated with this enzyme defect is called hereditary coproporphyria
.
It is an enzyme involved in the sixth step of porphyrin
metabolism it catalyses
the oxidative decarboxylation
of coproporphyrinogen III
to proto-porphyrinogen IX
in the haem and chlorophyll
biosynthetic pathways. The protein
is a homodimer containing two internally bound iron
atom
s per molecule
of native protein. The enzyme
is active in the presence of molecular oxygen
that acts as an electron
acceptor. The enzyme is widely distributed having been found in a variety of eukaryotic and prokaryotic sources.
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 in humans is encoded by the CPOX gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
. A genetic defect in the enzyme results in a reduced production of 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...
in animals. The medical condition associated with this enzyme defect is called hereditary coproporphyria
Hereditary coproporphyria
Hereditary coproporphyria is a type of acute porphyria that is associated with a deficiency of the enzyme coproporphyrinogen III oxidase....
.
It is an enzyme involved in the sixth step of porphyrin
Porphyrin
Porphyrins are a group of organic compounds, many naturally occurring. One of the best-known porphyrins is heme, the pigment in red blood cells; heme is a cofactor of the protein hemoglobin. Porphyrins are heterocyclic macrocycles composed of four modified pyrrole subunits interconnected at...
metabolism it catalyses
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 decarboxylation
Decarboxylation
Decarboxylation is a chemical reaction that releases carbon dioxide . Usually, decarboxylation refers to a reaction of carboxylic acids, removing a carbon atom from a carbon chain. The reverse process, which is the first chemical step in photosynthesis, is called carbonation, the addition of CO2 to...
of coproporphyrinogen III
Coproporphyrinogen III
In the metabolism of porphyrin, the enzyme uroporphyrinogen III decarboxylase generates coproporphyrinogen III from uroporphyrinogen III, and coproporphyrinogen III oxidase converts it into protoporphyrinogen IX....
to proto-porphyrinogen IX
Protoporphyrinogen IX
Protoporphyrinogen IX is a precursor for protoporphyrin IX. See Porphyrins for the pathway and more information.-See also:* Protoporphyrinogen oxidase...
in the haem and chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
biosynthetic pathways. The protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
is a homodimer containing two internally bound iron
Iron
Iron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
atom
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
s per molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
of native protein. The 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...
is active in the presence of molecular oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
that acts as an electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
acceptor. The enzyme is widely distributed having been found in a variety of eukaryotic and prokaryotic sources.
Further reading