Xylose isomerase

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xylose isomerase
D-Xylose isomerase tetramer from Streptomyces rubiginosus PDB 2glk.[1] One monomer is coloured by secondary structure to highlight the TIM barrel architecture.
EC number
CAS number 9023-82-9
IntEnz IntEnz view
ExPASy NiceZyme view
MetaCyc metabolic pathway
PRIAM profile
PDB structures RCSB PDB PDBe PDBsum
Gene Ontology AmiGO / EGO

In enzymology, a xylose isomerase (EC is an enzyme that catalyzes the chemical reaction

D-xylose \rightleftharpoons D-xylulose


This enzyme belongs to the family of isomerases, specifically those intramolecular oxidoreductases interconverting aldoses and ketoses. It participates in pentose and glucuronate interconversions and fructose and mannose metabolism. It is used industrially to convert glucose to fructose in the manufacture of high-fructose corn syrup.[2]


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.

Structural studies[edit]

Xylose isomerase enzymes exhibit a TIM barrel fold with the active site in the centre of the barrel and a tetrameric quaternary structure.[3] PDB structures are available in the links in the infobox to the right.


  1. ^ Katz, A. K.; Li, X.; Carrell, H. L.; Hanson, B. L.; Langan, P.; Coates, L.; Schoenborn, B. P.; Glusker, J. P.; Bunick, G. J. (2006). "Locating active-site hydrogen atoms in D-xylose isomerase: Time-of-flight neutron diffraction". Proceedings of the National Academy of Sciences 103 (22): 8342–8347. doi:10.1073/pnas.0602598103. PMC 1482496. PMID 16707576.  edit
  2. ^ Bhosale SH, Rao MB, Deshpande VV (June 1996). "Molecular and industrial aspects of glucose isomerase". Microbiological Reviews 60 (2): 280–300. PMC 239444. PMID 8801434. 
  3. ^ http://www.ebi.ac.uk/pdbe-srv/PDBeXplore/enzyme/?ec=

Further reading[edit]