EC - 6-phospho-3-hexuloisomerase

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IntEnz Enzyme Nomenclature


Accepted name:
Other names:
3-hexulose-6-phosphate isomerase
6-phospho-3-hexulose isomerase
Systematic name:
D-arabino-hex-3-ulose-6-phosphate isomerase



This enzyme, along with EC, 3-hexulose-6-phosphate synthase, plays a key role in the ribulose-monophosphate cycle of formaldehyde fixation, which is present in many microorganisms that are capable of utilizing C1-compounds [1]. The hyperthermophilic and anaerobic archaeon Pyrococcus horikoshii OT3 constitutively produces a bifunctional enzyme that sequentially catalyses the reactions of EC (3-hexulose-6-phosphate synthase) and this enzyme [4].

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Protein domains and families: PROSITE:PDOC51464
Structural data: CSA , EC2PDB


  1. Ferenci, T., Strøm, T. and Quayle, J.R.
    Purification and properties of 3-hexulose phosphate synthase and phospho-3-hexuloisomerase from Methylococcus capsulatus.
    Biochem. J. 144: 477-486 (1974). [PMID: 4219834]
  2. Yurimoto, H., Kato, N. and Sakai, Y.
    Assimilation, dissimilation, and detoxification of formaldehyde, a central metabolic intermediate of methylotrophic metabolism.
    Chem. Rec. 5: 367-375 (2005). [PMID: 16278835]
  3. Kato, N., Yurimoto, H. and Thauer, R.K.
    The physiological role of the ribulose monophosphate pathway in bacteria and archaea.
    Biosci. Biotechnol. Biochem. 70: 10-21 (2006). [PMID: 16428816]
  4. Orita, I., Yurimoto, H., Hirai, R., Kawarabayasi, Y., Sakai, Y. and Kato, N.
    The archaeon Pyrococcus horikoshii possesses a bifunctional enzyme for formaldehyde fixation via the ribulose monophosphate pathway.
    J. Bacteriol. 187: 3636-3642 (2005). [PMID: 15901685]
  5. Martinez-Cruz, L.A., Dreyer, M.K., Boisvert, D.C., Yokota, H., Martinez-Chantar, M.L., Kim, R. and Kim, S.H.
    Crystal structure of MJ1247 protein from M. jannaschii at 2.0 Å resolution infers a molecular function of 3-hexulose-6-phosphate isomerase.
    Structure 10: 195-204 (2002). [PMID: 11839305]
  6. Taylor, E.J., Charnock, S.J., Colby, J., Davies, G.J. and Black, G.W.
    Cloning, purification and characterization of the 6-phospho-3-hexulose isomerase YckF from Bacillus subtilis.
    Acta Crystallogr. D Biol. Crystallogr. 57: 1138-1140 (2001). [PMID: 11468398]

[EC created 2008]