EC - Inositol-3-phosphate synthase

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IntEnz Enzyme Nomenclature


Accepted name:
inositol-3-phosphate synthase
Other names:
myo-inositol-1-phosphate synthase
D-glucose 6-phosphate cycloaldolase
glucose 6-phosphate cyclase
glucose-6-phosphate inositol monophosphate cycloaldolase
inositol 1-phosphate synthatase
inositol 1-phosphate synthetase
1L-myo-inositol-1-phosphate lyase (isomerizing)
Systematic name:
1D-myo-inositol-3-phosphate lyase (isomerizing)




Requires NAD+, which dehydrogenates the -CHOH- group to -CO- at C-5 of the glucose 6-phosphate, making C-6 into an active methylene, able to condense with the -CHO at C-1. Finally, the enzyme-bound NADH reconverts C-5 into the -CHOH- form.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , DIAGRAM , DIAGRAM , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0004512
CAS Registry Number: 9032-95-5
UniProtKB/Swiss-Prot: (31) [show] [UniProt]


  1. Eisenberg, F., Jr.
    D-Myoinositol 1-phosphate as product of cyclization of glucose 6-phosphate and substrate for a specific phosphatase in rat testis.
    J. Biol. Chem. 242: 1375-1382 (1967). [PMID: 4290245]
  2. Sherman, W.R., Stewart, M.A. and Zinbo, M.
    Mass spectrometric study on the mechanism of D-glucose 6-phosphate-L-myo-inositol 1-phosphate cyclase.
    J. Biol. Chem. 244: 5703-5708 (1969). [PMID: 4310603]
  3. Barnett, J.E.G. and Corina, D.L.
    The mechanism of glucose 6-phosphate-D-myo-inositol 1-phosphate cyclase of rat testis. The involvement of hydrogen atoms.
    Biochem. J. 108: 125-129 (1968). [PMID: 4297937]
  4. Barnett, J.E.G., Rasheed, A. and Corina, D.L.
    Partial reactions of glucose 6-phosphate-1L-myo-inositol 1-phosphate cyclase.
    Biochem. J. 131: 21-30 (1973). [PMID: 4352864]

[EC created 1972, modified 2001]