In enzymology, a phytanoyl-CoA dioxygenase () is an

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecule ...

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 A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and break ...

:phytanoyl-CoA + 2-oxoglutarate + O₂

\rightleftharpoons

2-hydroxyphytanoyl-CoA + succinate + CO₂ Alpha oxidation part II

The three substrates of this enzyme are

phytanoyl-CoA Phytanoyl-CoA is a derivative of phytanic acid. See also * Phytanoyl-CoA hydroxylase {{Peroxisomal metabolism intermediates Thioesters of coenzyme A ...

, 2-oxoglutarate (2OG), and O₂, whereas its three products are 2-hydroxyphytanoyl-CoA, succinate, and CO₂. This enzyme belongs to the family of iron(II)-dependent oxygenases, which typically incorporate one atom of dioxygen into the substrate and one atom into the succinate carboxylate group. The mechanism is complex, but is believed to involve ordered binding of 2-oxoglutarate to the iron(II) containing enzyme followed by substrate. Binding of substrate causes displacement of a water molecule from the iron(II) cofactor, leaving a vacant coordination position to which dioxygen binds. A rearrangement occurs to form a high energy iron-oxygen species (which is generally thought to be an iron(IV)=O species) that performs the actual oxidation reaction.

Nomenclature

The systematic name of this enzyme class is phytanoyl-CoA, 2-oxoglutarate:oxygen oxidoreductase (2-hydroxylating). This enzyme is also called phytanoyl-CoA hydroxylase and phytanoyl-CoA alpha-hydroxylase.

Examples

In humans, phytanoyl-CoA hydroxylase is encoded by the ''PHYH'' (''aka PAHX'')

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

and is required for the alpha-oxidation of branched chain fatty acids (e.g. phytanic acid) in

peroxisomes A peroxisome () is a membrane-bound organelle, a type of microbody, found in the cytoplasm of virtually all eukaryotic cells. Peroxisomes are oxidative organelles. Frequently, molecular oxygen serves as a co-substrate, from which hydrogen pe ...

. PHYH deficiency results in the accumulation of large tissue stores of phytanic acid and is the major cause of Refsum disease.

Related enzymes

Iron(II) and 2OG-dependent oxygenases are common in

microorganism A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

s, plants, and animals; the

human genome The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the ...

is predicted to contain about 80 examples, and the model plant ''

Arabidopsis thaliana ''Arabidopsis thaliana'', the thale cress, mouse-ear cress or arabidopsis, is a small flowering plant native to Eurasia and Africa. ''A. thaliana'' is considered a weed; it is found along the shoulders of roads and in disturbed land. A winter ...

'' likely contains more. In plants and microorganisms this enzyme family is associated with a large diversity of oxidative reactions.

References

External links

GeneReviews/NCBI/NIH/UW entry on Refsum Disease
{{DEFAULTSORT:Phytanoyl-Coa Dioxygenase EC 1.14.11 Enzymes of known structure

Nomenclature

Examples

Related enzymes

References

Further reading

External links