Molybdenum cofactor
Encyclopedia
Molybdenum cofactor is a cofactor
required for the activity of enzyme
s such as sulfite oxidase
, xanthine oxidoreductase, and aldehyde oxidase
. It is a coordination complex formed between molybdopterin
(which, despite the name, does not contain molybdenum) and an oxide
of molybdenum
.
Molybdopterins, in turn, are synthesized from guanosine triphosphate
(see synthetic route at right).
Molybdenum cofactor functions directly in ethylbenzene dehydrogenase, glyceraldehyde-3-phosphate ferredoxin oxidoreductase, and respiratory arsenate reductase
In animals and plants these enzymes use molybdenum bound at the active site in a tricyclic molybdenum cofactor
. All molybdenum-using enzymes so far identified in nature use this cofactor, save for the phylogenetically ancient molybdenum nitrogenase
s, which fix nitrogen in some bacteria and cyanobacteria. Molybdenum enzymes in plants and animals catalyze the oxidation and sometimes reduction of certain small molecules, as part of the regulation of nitrogen
, sulfur
and carbon cycle
s.
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....
required for the activity of 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...
s such as sulfite oxidase
Sulfite oxidase
Sulfite oxidase is an enzyme in the mitochondria of all eukaryotes. It oxidizes sulfite to sulfate and, via cytochrome c, transfers the electrons produced to the electron transport chain, allowing generation of ATP in oxidative phosphorylation...
, xanthine oxidoreductase, and aldehyde oxidase
Aldehyde oxidase
Aldehyde oxidase is an enzyme which generates carboxylic acids from aldehydes. It catalyzes the conversion of an aldehyde in the presence of oxygen and water to an acid and hydrogen peroxide.* an aldehyde + H2O + O2 a carboxylate + H2O2 + H+...
. It is a coordination complex formed between molybdopterin
Molybdopterin
Molybdopterins, when reacted with molybdenum or tungsten in the form of molybdate or tungstate, are a class of cofactors found in most molybdenum and all tungsten enzymes...
(which, despite the name, does not contain molybdenum) and an oxide
Oxide
An oxide is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2....
of molybdenum
Molybdenum
Molybdenum , is a Group 6 chemical element with the symbol Mo and atomic number 42. The name is from Neo-Latin Molybdaenum, from Ancient Greek , meaning lead, itself proposed as a loanword from Anatolian Luvian and Lydian languages, since its ores were confused with lead ores...
.
Molybdopterins, in turn, are synthesized from guanosine triphosphate
Guanosine triphosphate
Guanosine-5'-triphosphate is a purine nucleoside triphosphate. It can act as a substrate for the synthesis of RNA during the transcription process...
(see synthetic route at right).
Molybdenum cofactor functions directly in ethylbenzene dehydrogenase, glyceraldehyde-3-phosphate ferredoxin oxidoreductase, and respiratory arsenate reductase
In animals and plants these enzymes use molybdenum bound at the active site in a tricyclic molybdenum cofactor
Molybdenum cofactor
Molybdenum cofactor is a cofactor required for the activity of enzymes such as sulfite oxidase, xanthine oxidoreductase, and aldehyde oxidase. It is a coordination complex formed between molybdopterin and an oxide of molybdenum.Molybdopterins, in turn, are synthesized from guanosine triphosphate...
. All molybdenum-using enzymes so far identified in nature use this cofactor, save for the phylogenetically ancient molybdenum nitrogenase
Nitrogenase
Nitrogenases are enzymes used by some organisms to fix atmospheric nitrogen gas . It is the only known family of enzymes that accomplish this process. Dinitrogen is quite inert because of the strength of its N-N triple bond...
s, which fix nitrogen in some bacteria and cyanobacteria. Molybdenum enzymes in plants and animals catalyze the oxidation and sometimes reduction of certain small molecules, as part of the regulation of nitrogen
Nitrogen cycle
The nitrogen cycle is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out by both biological and non-biological processes. Important processes in the nitrogen cycle include fixation, mineralization, nitrification, and denitrification...
, sulfur
Sulfur cycle
The sulfur cycle are the collection of processes by which sulfur moves to and from minerals and living systems. Such biogeochemical cycles are important in geology because they affect many minerals...
and carbon cycle
Carbon cycle
The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth...
s.
See also
- Molybdenum cofactor deficiencyMolybdenum cofactor deficiencyMolybdenum cofactor deficiency is a human disease. Absence of molybdenum cofactor leads to accumulation of toxic levels of sulphite and neurological damage usually leading to death within months of birth, due to the lack of active sulfite oxidase...
, a genetic illness. - MOCS1MOCS1Molybdenum cofactor biosynthesis protein 1 is a protein that in humans is encoded by the MOCS1 gene.Both copies of this gene are defective in patients with molybdenum cofactor deficiency, type A.-Further reading:...
, MOCS2MOCS2Molybdenum cofactor synthesis protein 2A and molybdenum cofactor synthesis protein 2B are a pair of proteins that in humans are encoded from the same MOCS2 gene...
, MOCS3MOCS3Adenylyltransferase and sulfurtransferase MOCS3 is an enzyme that in humans is encoded by the MOCS3 gene.-Further reading:...
, GEPH