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{{enzyme
| Name = xylose isomerase
| EC_number = 5.3.1.5
| CAS_number = 9023-82-9
| IUBMB_EC_number = 5/3/1/5
| GO_code = 0009045
| image = 2glk.png
| width = 
| caption = D-Xylose isomerase tetramer from ''Streptomyces rubiginosus'' [[Protein Data Bank|PDB]] {{PDBe|2glk}}.<ref>{{cite pmid|16707576}}</ref> One monomer is coloured by secondray structure to highlight the TIM barrel architecture.
}}
In [[enzymology]], a '''xylose isomerase''' ({{EC number|5.3.1.5}}) is an [[enzyme]] that [[catalysis|catalyzes]] the [[chemical reaction]]

:[[D-xylose]] <math>\rightleftharpoons</math> [[D-xylulose]]

This enzyme belongs to the family of [[isomerase]]s, specifically those intramolecular [[oxidoreductase]]s interconverting [[aldose]]s and [[ketose]]s.  The systematic name of this enzyme class is '''D-xylose aldose-ketose-isomerase'''. Other names in common use include '''D-xylose isomerase''', '''D-xylose ketoisomerase''', and '''D-xylose ketol-isomerase'''.  This enzyme participates in [[pentose and glucuronate interconversions]] and [[fructose]] and [[mannose]] metabolism.  The enzyme is used industrially to convert glucose to fructose in the manufacture of [[high-fructose corn syrup]]. It is sometimes referred to as "'''glucose isomerase'''".

==Structural studies==

Xylose isomerase enzymes exhibit a [[TIM barrel]] fold with the active site in the centre of the barrel and a [[tetrameric]] [[quaternary structure]].<ref>http://www.ebi.ac.uk/pdbe-srv/PDBeXplore/enzyme/?ec=5.3.1.5&tab=assemblies</ref> PDB structures are available in the links in the infobox to the right.

==References==
{{reflist|1}}
* {{cite journal | author = HOCHSTER RM, WATSON RW | year = 1954 | title = Enzymatic isomerization of D-xylose to D-xylulose | journal = Arch. Biochem. Biophys.  | volume = 48 | pages = 120&ndash;9  | pmid = 13125579 | doi = 10.1016/0003-9861(54)90313-6 | issue = 1 }}
* {{cite journal | author = Slein MW | year = 1955 | title = Xylose isomerase from Pasteurella pestis, strain A-1122 | journal = J. Am. Chem. Soc.  | volume = 77 | pages = 1663&ndash;1667 | doi = 10.1021/ja01611a074 | issue = 6 }}
* {{cite journal | author = Yamanaka K | year = 1968 | title = Purification, crystallization and properties of the D-xylose isomerase from Lactobacillus brevis | journal = Biochim. Biophys. Acta.  | volume = 151 | pages = 670&ndash;80  | pmid = 5646045 | issue = 3 }}

[[Category:EC 5.3.1]]
[[Category:Enzymes of known structure]]


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