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			{{Short description|Heterocyclic ligand that can complex molybdenum to form a Mo-cofactor}}
	{{chembox		{{chembox
			| Watchedfields = changed
	| verifiedrevid = 408052759
			| verifiedrevid = 444327795
	|ImageFile=MoPterin.png
			| ImageFile=MoPterin.png
	|ImageSize=300px
			| ImageSize=300px
	|ImageFile2=
			| ImageFile2=
	|ImageSize2=
			| ImageSize2=
	|IUPACName=
			| IUPACName=pteridin-8-yl]methyl dihydrogen phosphate<ref>{{cite web |title=HPEUEJRPDGMIMY-UHFFFAOYSA-N |url=https://pubchem.ncbi.nlm.nih.gov/compound/135402014#section=IUPAC-Name |website=pubchem.ncbi.nlm.nih.gov |accessdate=4 February 2019 |language=en |quote=IUPAC Name pteridin-8-yl]methyl dihydrogen phosphate}}</ref>
	|OtherNames=
			| OtherNames=
	|Section1= {{Chembox Identifiers
			|Section1={{Chembox Identifiers
	| CASNo=73508-07-3
			| CASNo_Ref = {{cascite|correct|CAS}}
	| PubChem=459
			| CASNo=73508-07-3
	| SMILES=
			| UNII_Ref = {{fdacite|correct|FDA}}
	| MeSHName=molybdopterin
			| UNII = ATN6EG42UQ
	}}
			| PubChem=135402014
	|Section2= {{Chembox Properties
			| SMILES=NC(=N1)NC(=O)C2=C1N3(N2)C(S)=C(S)(O3)COP()()=O
	| Formula=C<sub>10</sub>H<sub>10</sub>N<sub>5</sub>O<sub>6</sub>PS<sub>2</sub> + R groups
			| SMILES_Comment=based on the images on this page
	| MolarMass=394.33 g/mol (R=H)
			| SMILES1=C(C1C(=C(C2C(O1)NC3=C(N2)C(=O)NC(=N3)N)S)S)OP(=O)(O)O
	| Appearance=
			| SMILES1_Comment=from ; several discrepancies with images on this page
	| Density=
			| SMILES2=NC(=N1)NC(=O)C2=C1N3(N2)C(S4)=C(S4(=O)(=O)O)(O3)COP()()=O
	| MeltingPt=
			| SMILES2_Comment=with molybdenum; based on ]
	| BoilingPt=
			| MeSHName=molybdopterin
	| Solubility=
			| InChI=1S/C10H14N5O6PS2/c11-10-14-7-4(8(16)15-10)12-3-6(24)5(23)2(21-9(3)13-7)1-20-22(17,18)19/h2-3,9,12,23-24H,1H2,(H2,17,18,19)(H4,11,13,14,15,16)
	}}
			| InChI_Comment=<ref>{{cite web |title=HPEUEJRPDGMIMY-UHFFFAOYSA-N |url=https://pubchem.ncbi.nlm.nih.gov/compound/135402014#section=InChI |website=pubchem.ncbi.nlm.nih.gov |accessdate=4 February 2019 |language=en |quote=InChI InChI=1S/C10H14N5O6PS2/c11-10-14-7-4(8(16)15-10)12-3-6(24)5(23)2(21-9(3)13-7)1-20-22(17,18)19/h2-3,9,12,23-24H,1H2,(H2,17,18,19)(H4,11,13,14,15,16)}}</ref>
	|Section3= {{Chembox Hazards
			| InChIKey=HPEUEJRPDGMIMY-UHFFFAOYSA-N<ref>{{cite web |title=pteridin-8-yl]methyl dihydrogen phosphate |url=https://pubchem.ncbi.nlm.nih.gov/compound/135402014#section=Top |website=pubchem.ncbi.nlm.nih.gov |accessdate=4 February 2019 |language=en |quote=InChI=1S/C10H14N5O6PS2/c11-10-14-7-4(8(16)15-10)12-3-6(24)5(23)2(21-9(3)13-7)1-20-22(17,18)19/h2-3,9,12,23-24H,1H2,(H2,17,18,19)(H4,11,13,14,15,16)}}</ref><ref>{{cite web |title=HPEUEJRPDGMIMY-UHFFFAOYSA-N |url=https://pubchem.ncbi.nlm.nih.gov/compound/135402014#section=InChI-Key |website=pubchem.ncbi.nlm.nih.gov |accessdate=4 February 2019 |language=en |quote=InChI Key HPEUEJRPDGMIMY-UHFFFAOYSA-N}}</ref>
	| MainHazards=
	| FlashPt=
	| Autoignition=
	}}
	}}		}}
			|Section2={{Chembox Properties
	]
			| Formula={{chem|C|10|H|10|N|5|O|6|PS|2}} + R groups
	'''Molybdopterins''', when reacted with molybdenum or tungsten in the form of molybdate or tungstate, are a class of ] found in most ] (Mo) and all ] (W) enzymes. Synonyms for molydopterin are: '''MPT''' and '''pyranopterin-dithiolate.'''
			| MolarMass=394.33 g/mol (R=H)
			| Appearance=
			| Density=
			| MeltingPt=
			| BoilingPt=
			| Solubility=
			}}
			}}
			]
			'''Molybdopterins''' are a class of ] found in most ]-containing and all ]-containing enzymes. Synonyms for molybdopterin are: '''MPT''' and '''pyranopterin-dithiolate.''' The nomenclature for this biomolecule can be confusing: Molybdopterin itself contains no molybdenum; rather, this is the name of the ligand (a '']'') that will bind the active metal. After molybdopterin is eventually complexed with molybdenum, the complete ligand is usually called ].
			Molybdopterin consists of a pyranopterin, a complex ] featuring a ] fused to a ] ring. In addition, the pyran ring features two ]s, which serve as ]s in molybdo- and tungstoenzymes. In some cases, the alkyl phosphate group is replaced by an alkyl diphosphate ]. Enzymes that contain the molybdopterin cofactor include ], ], ], and ].
	The nomenclature for this biomolecule can be confusing: molybdopterin ''per se'' contains no molybdenum; rather, this is the name of the ligand that will eventually bind the active metal. After molydopterin is eventually complexed with molybdate, the complete ligand is usually called ].
			The only molybdenum-containing enzymes that do not feature molybdopterins are the ]s (enzymes that fix nitrogen). These contain an iron-sulfur center of a very different type, which also contains molybdenum.<ref name="gramene"> {{Webarchive|url=https://web.archive.org/web/20160604060520/http://pathway.gramene.org/META/NEW-IMAGE?type=COMPOUND&object=CPD-4 |date=2016-06-04 }} Accessed Nov. 16, 2009.</ref>
	Molydopterin consists of a pyranopterin, a complex ] featuring a ] fused to a ] ring. In addition, the pyran ring features two ]s, which serve as ]s in molybdo- and tungstoenzymes. In some cases, the alkyl phosphate group is replaced by an alkyl diphosphate ]. Enzymes that contain the molybdopterin cofactor include ], ], ], and ].
	The only molybdenum-containing enzymes that do not feature molydopterins are the ]s (enzymes that fix nitrogen). These contain an iron-sulfur center of a very different type, which also usually contains molybdenum. However, if molybdenum is present, it is directly bonded to other metal atoms. <ref> Structure, synthesis, empirical formula for the di-sulfhydryl. Accessed Nov. 16, 2009.</ref>
	==Biosynthesis==		==Biosynthesis==
			Unlike many other cofactors, molybdenum cofactor (Moco) cannot be taken up as a nutrient. The cofactor thus requires ]. Molybdenum cofactor biosynthesis occurs in four steps: (i) the radical-mediated cyclization of nucleotide, ] (GTP), to ] ({{nobr|3',8‑cH<sub>2</sub>GTP}}), (ii) the formation of ] (cPMP) from the {{nobr|3',8‑cH<sub>2</sub>GTP}}, (iii) the conversion of cPMP into molybdopterin (MPT), (iv) the insertion of molybdate into MPT to form Moco.<ref name="pmid25941396"/><ref name="pmid23627491"/>
	The ] of molybdopterin begins with ] triphosphate. Two enzymatic reactions convert this triphosphate to the cyclic phosphate of pyranopterin. One of these enzymes utilizes radical SAMs, often associated with C—X bond-forming reactions. This intermediate pyranopterin is then converted to the molybdopterin via the action of three further enzymes. In this conversion, the enedithiolate is formed, although the substituents on sulfur remain unknown. Sulfur is conveyed from cysteinyl persulfide in a manner reminiscent of the biosynthesis of ]s. The monophosphate is adenylated (coupled to ADP) in a step that activates the cofactor toward binding Mo or W. These metals are imported as their oxyanions, ], and ]. Finally, Mo or W is inserted to give the molybdopterin cofactor. In some enzymes, such as ], the metal is bound to one molybdopterin, whereas, in other enzymes, e.g., ], the metal is bound to two molybdopterin cofactors.<ref>{{cite journal
	| author = Schwarz, G. and Mendel, R. R.
	| title = Molybdenum cofactor biosynthesis and molybdenum enzymes
	| journal = Annu. Rev. Plant Biol.
	| year = 2006
	| volume = 57
	| pages = 623–647
	| doi = 10.1146/annurev.arplant.57.032905.105437
	| pmid = 16669776
	}}</ref>
			Two enzyme-mediated reactions convert ] to the cyclic phosphate of pyranopterin. One of these enzymes is a ], a family of enzymes often associated with C—X bond-forming reactions (X = S, N).<ref>{{cite journal|author1=Mendel, R. R. |author2=Leimkuehler, S. |title=The biosynthesis of the molybdenum cofactors|journal=J. Biol. Inorg. Chem.|year=2015|volume=20|issue=2|pages=337–347|doi=10.1007/s00775-014-1173-y|pmid=24980677|s2cid=2638550}}</ref><ref name="pmid23627491">{{cite journal |vauthors=Hover BM, Loksztejn A, Ribeiro AA, Yokoyama K | title = Identification of a cyclic nucleotide as a cryptic intermediate in molybdenum cofactor biosynthesis | journal = J Am Chem Soc | volume = 135 | issue = 18 | pages = 7019–32 |date=April 2013 | doi = 10.1021/ja401781t | pmid = 23627491 | pmc=3777439}}</ref><ref name="pmid25941396">{{cite journal |vauthors=Hover BM, Tonthat NK, Schumacher MA, Yokoyama K | title = Mechanism of pyranopterin ring formation in molybdenum cofactor biosynthesis | journal = Proc Natl Acad Sci USA | volume = 112| issue = 20| pages = 6347–52|date=May 2015 | doi = 10.1073/pnas.1500697112| pmid = 25941396 | pmc=4443348| bibcode = 2015PNAS..112.6347H | doi-access = free }}</ref> This intermediate pyranopterin is then converted to the molybdopterin via the action of three further enzymes. In this conversion, the enedithiolate is formed, although the substituents on sulfur remain unknown. ] is conveyed from cysteinyl persulfide in a manner reminiscent of the biosynthesis of ]s. The monophosphate is adenylated (coupled to ADP) in a step that activates the cofactor toward binding Mo or W. These metals are imported as their oxyanions, ], and ].
	Models for the active sites of enzymes molybdopterin-containing enzymes are based on a class of ligands known as ]s.<ref>{{cite journal
	| author = Kisker, C.; Schindelin, H.; Baas, D.; Rétey, J.; Meckenstock, R.U.; Kroneck, P.M.H.
	| title = A structural comparison of molybdenum cofactor-containing enzymes
	| journal = FEMS Microbiol. Rev.
	| year = 1999
	| volume = 22
	| pages = 503–521
	| doi = 10.1111/j.1574-6976.1998.tb00384.x
	| pmid = 9990727
	| issue = 5
	}} {{PMID|9990727}}
	</ref>
			In some enzymes, such as ], the metal is bound to one molybdopterin, whereas, in other enzymes, e.g., ], the metal is bound to two molybdopterin cofactors.<ref>{{cite journal |author1=Schwarz, G. |author2=Mendel, R. R. |name-list-style=amp | title = Molybdenum cofactor biosynthesis and molybdenum enzymes| journal = Annual Review of Plant Biology | year = 2006 | volume = 57 | pages = 623–647 | doi = 10.1146/annurev.arplant.57.032905.105437 | pmid = 16669776 }}</ref>
	== Selenium-containing version, and ability to bind active tungsten ==
	Tungsten has not been found to be necessary or used in eukaryotes, but it is an ] for some bacteria. For example, ]s called ]s use tungsten in a similar manner as ] by using it in a tungsten-] complex with molybdopterin. Thus, molybdopterin may complex with either molybdenum or tungsten in use by bacteria. Tungsten-using enzymes typically reduce free carboxylic acids to aldehydes.<ref name="tungsten_orgs">{{cite book|last=Lassner|first=Erik|title=Tungsten: Properties, Chemistry, Technology of the Element, Alloys and Chemical Compounds|publisher=Springer|year=1999|pages=409–411|isbn=0306450534|url=http://books.google.com/?id=foLRISkt9gcC&pg=PA409&lpg=PA409&dq=tungsten+nutrient+organisms}}</ref> The first tungsten-requiring enzyme to be discovered also requires selenium, and in this case the tungsten-selenium pair may function analogously to the molybdenum-sulfur pairing of some ]-requiring enzymes.<ref>{{cite journal| url = http://media.iupac.org/publications/pac/1998/pdf/7004x0889.pdf| title = Transition metal sulfur chemistry and its relevance to molybdenum and tungsten enzymes| author = Stiefel, E. I.| journal = Pure & Appl. Chem.| volume =70|issue = 4|pages = 889–896|year = 1998| doi = 10.1351/pac199870040889}}</ref> One of the enzymes in the oxidoreductase family which sometimes employ tungsten (bacterial ] H) is known to use a selenium-molybdenum version of molybdopterin.<ref>{{cite journal|doi=10.1021/bi972177k |title=Selenium-Containing Formate Dehydrogenase H from Escherichia coli: A Molybdopterin Enzyme That Catalyzes Formate Oxidation without Oxygen Transfer|journal= Biochemistry|year= 1998|volume=37|pages=3518–3528|author=Khangulov, S. V. ''et al.''|pmid=9521673|issue=10}}</ref> Although a tungsten-containing xanthine dehydrogenase from bacteria has been found to contain tungsten-molydopterin and also non-protein bound selenium, a tungsten-selenium molybdopterin complex has not been definitively described.<ref>Eur J Biochem 1999 Sep;264(3):862-71</ref>
			Models for the active sites of enzymes molybdopterin-containing enzymes are based on a class of ligands known as ]s.<ref>{{cite journal |author1=Kisker, C. |author2=Schindelin, H. |author3=Baas, D. |author4=Rétey, J. |author5=Meckenstock, R.U. |author6=Kroneck, P.M.H. | title = A structural comparison of molybdenum cofactor-containing enzymes | journal = FEMS Microbiol. Rev. | year = 1999 | volume = 22 | pages = 503–521 | doi = 10.1111/j.1574-6976.1998.tb00384.x| pmid=9990727 | issue = 5| doi-access=free}}</ref>
	== Enzymes that use molydopterin as cofactor or prosthetic group ==
	Cofactor of: ], ], ], ], ], ], ]
			== Tungsten derivatives==
	Prosthetic Group of: ], ], ]
			Some bacterial oxidoreductases use ] in a similar manner as ] by using it in a tungsten-] complex, with molybdopterin. Thus, molybdopterin may complex with either molybdenum or tungsten. Tungsten-using enzymes typically reduce free carboxylic acids to aldehydes.<ref name="tungsten_orgs">{{cite book|last=Lassner|first=Erik|title=Tungsten: Properties, Chemistry, Technology of the Element, Alloys and Chemical Compounds|publisher=Springer|year=1999|pages=409–411 |isbn=978-0-306-45053-2 |url=https://books.google.com/books?id=foLRISkt9gcC&q=tungsten+nutrient+organisms&pg=PA409}}</ref>
			The first tungsten-requiring enzyme to be discovered also requires selenium (though the precise form is unknown). In this case, the tungsten-selenium pair has been speculated to function analogously to the molybdenum-sulfur pairing of some molybdenum cofactor-requiring enzymes.<ref>{{cite journal| url = http://media.iupac.org/publications/pac/1998/pdf/7004x0889.pdf| title = Transition metal sulfur chemistry and its relevance to molybdenum and tungsten enzymes| author = Stiefel, E. I.| journal = Pure Appl. Chem.| volume =70|issue = 4|pages = 889–896|year = 1998| doi = 10.1351/pac199870040889| s2cid = 98647064}}</ref> Although a tungsten-containing xanthine dehydrogenase from bacteria has been found to contain tungsten-molybdopterin and ''also'' non-protein-bound selenium (thus removing the possibility of selenium in ] or ] form), a tungsten-selenium molybdopterin complex has not been definitively described.<ref>{{cite journal |vauthors=Schräder T, Rienhöfer A, Andreesen JR |title=Selenium-containing xanthine dehydrogenase from ''Eubacterium barkeri'' |journal=Eur. J. Biochem. |volume=264 |issue=3 |pages=862–71 |date=September 1999 |pmid=10491134 |doi=10.1046/j.1432-1327.1999.00678.x|doi-access=free}}</ref>
	See <ref> Structure, synthesis, empirical formula for the di-sulfhydryl. Accessed Nov. 16, 2009.</ref>
			== Enzymes that use molybdopterin ==
			Enzymes that use molybdopterin as cofactor or ] are given below.<ref name="gramene" /> Molybdopterin is a:
			*Cofactor of: ], ], ], ], ], ], ], ], ].
			*Prosthetic group of: ], ], ].
			==See also==
			*], a genetic illness.
			*], molybdenum cofactor sulfurase
			*], ], ], ]
	==References==		==References==
			{{reflist|1}}
	<references/>
	{{Enzyme cofactors}}		{{Enzyme cofactors}}
			{{Metabolism of vitamins, coenzymes, and cofactors}}
			]
	]		]
	]		]
	]		]
			]
			]
	]
	]
	]