Reaction: D-arabino-hex-3-ulose 6-phosphate = D-ribulose 5-phosphate + formaldehyde
For diagram of reaction, click here
Other name(s): D-arabino-3-hexulose 6-phosphate formaldehyde-lyase; 3-hexulosephosphate synthase; 3-hexulose phosphate synthase; HPS
Systematic name: D-arabino-3-hexulose-6-phosphate formaldehyde-lyase (D-ribulose-5-phosphate-forming)
Comments: Requires Mg2+ or Mn2+ for maximal activity . The enzyme is specific for formaldehyde and D-ribulose 5-phosphate as substrates. Ribose 5-phosphate, xylulose 5-phosphate, allulose 6-phosphate and fructose 6-phosphate cannot act as substrate. This enzyme, along with EC 188.8.131.52, 6-phospho-3-hexuloisomerase, 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 . The hyperthermophilic and anaerobic archaeon Pyrococcus horikoshii OT3 constitutively produces a bifunctional enzyme that sequentially catalyses the reactions of this enzyme and EC 184.108.40.206, 6-phospho-3-hexuloisomerase . This enzyme is a member of the orotidine 5'-monophosphate decarboxylase (OMPDC) suprafamily .
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:
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 (1974) 477-486. [PMID: 4219834]
2. Kato, N., Ohashi, H., Tani, Y. and Ogata, K. 3-Hexulosephosphate synthase from Methylomonas aminofaciens 77a. Purification, properties and kinetics. Biochim. Biophys. Acta 523 (1978) 236-244. [PMID: 564713]
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6. 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 (2005) 3636-3642. [PMID: 15901685]
7. Kato, N., Miyamoto, N., Shimao, M. and Sakazawa, C. 3-Hexulose phosphate pynthase from a new facultative methylotroph, Mycobacterium gastri MB19. Agric. Biol. Chem. 52 (1988) 265-2661.