EC - Xylose isomerase

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IntEnz Enzyme Nomenclature


Accepted name:
xylose isomerase
Other names:
D-xylose isomerase
D-xylose ketoisomerase
D-xylose ketol-isomerase
Systematic name:
α-D-xylose aldose-ketose-isomerase




Contains two divalent metal ions, preferably magnesium, located at different metal-binding sites within the active site. The enzyme catalyses the interconversion of aldose and ketose sugars with broad substrate specificity. The enzyme binds the closed form of its sugar substrate (in the case of glucose, only the α anomer) and catalyses ring opening to generate a form of open-chain conformation that is coordinated to one of the metal sites. Isomerization proceeds via a hydride-shift mechanism.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC00156
Structural data: CSA , EC2PDB
Gene Ontology: GO:0009045
CAS Registry Number: 9023-82-9
UniProtKB/Swiss-Prot: (198) [show] [UniProt]


  1. Hochster, R.M. and Watson, R.W.
    Enzymatic isomerization of D-xylose to D-xylulose.
    Arch. Biochem. Biophys. 48 : 120-129 (1954). [PMID: 13125579]
  2. Slein, M.W.
    Xylose isomerase from Pasteurella pestis, strain A-1122.
    J. Am. Chem. Soc. 77 : 1663-1667 (1955).
  3. Yamanaka, K.
    Purification, crystallization and properties of the D-xylose isomerase from Lactobacillus brevis.
    Biochim. Biophys. Acta 151 : 670-680 (1968). [PMID: 5646045]
  4. Carrell, H. L., Glusker, J. P., Burger, V., Manfre, F., Tritsch, D., Biellmann, J. F.
    X-ray analysis of D-xylose isomerase at 1.9 A: native enzyme in complex with substrate and with a mechanism-designed inactivator.
    Proc. Natl. Acad. Sci. U.S.A. 86 : 4440-4444 (1989). [PMID: 2734296]
  5. Collyer, C. A., Blow, D. M.
    Observations of reaction intermediates and the mechanism of aldose-ketose interconversion by D-xylose isomerase.
    Proc. Natl. Acad. Sci. U.S.A. 87 : 1362-1366 (1990). [PMID: 2304904]
  6. Whitlow, M., Howard, A. J., Finzel, B. C., Poulos, T. L., Winborne, E., Gilliland, G. L.
    A metal-mediated hydride shift mechanism for xylose isomerase based on the 1.6 A Streptomyces rubiginosus structures with xylitol and D-xylose.
    Proteins 9 : 153-173 (1991). [PMID: 2006134]
  7. Allen, K. N., Lavie, A., Glasfeld, A., Tanada, T. N., Gerrity, D. P., Carlson, S. C., Farber, G. K., Petsko, G. A., Ringe, D.
    Role of the divalent metal ion in sugar binding, ring opening, and isomerization by D-xylose isomerase: replacement of a catalytic metal by an amino acid.
    Biochemistry 33 : 1488-1494 (1994). [PMID: 7906142]
  8. Schray, K. J., Rose, I. A.
    Anomeric specificity and mechanism of two pentose isomerases.
    Biochemistry 10 : 1058-1062 (1971). [PMID: 5550812]

[EC created 1961 (EC created 1972, part incorporated 1978)]