EC - Heparosan-N-sulfate-glucuronate 5-epimerase

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IntEnz Enzyme Nomenclature


Accepted name:
heparosan-N-sulfate-glucuronate 5-epimerase
Other names:
D-glucuronyl C-5 epimerase
C-5 uronosyl epimerase
heparosan epimerase
heparosan-N-sulfate-D-glucuronosyl 5-epimerase
polyglucuronate epimerase
poly[(1,4)-β-D-glucuronosyl-(1,4)-N-sulfo-α-D-glucosaminyl] glucurono-5-epimerase
Systematic name:
poly[(1→4)-β-D-glucuronosyl-(1→4)-N-sulfo-α-D-glucosaminyl] glucurono-5-epimerase



The enzyme acts on D-glucosyluronate residues in N-sulfated heparosan polymers, converting them to L-iduronate, thus modifying the polymer to heparan-N-sulfate. The enzyme requires that at least the N-acetylglucosamine residue linked to C-4 of the substrate has been deacetylated and N-sulfated, and activity is highest with fully N-sulfated substrate. It does not act on glucuronate residues that are O-sulfated or are adjacent to N-acetylglucosamine residues that are O-sulfated at the 6 position. Thus the epimerization from D-glucuronate to L-iduronate occurs after N-sulfation of glucosamine residues but before O-sulfation. Not identical with EC, chondroitin-glucuronate 5-epimerase or with EC, heparosan-glucuronate 5-epimerase.

Links to other databases

Enzymes and pathways: NC-IUBMB , BRENDA , ExplorEnz , ENZYME@ExPASy , KEGG , MetaCyc , UniPathway
Structural data: CSA , EC2PDB
Gene Ontology: GO:0047464
CAS Registry Number: 112567-86-9


  1. Jacobsson, I., Bäckström, G., Höök, M., Lindahl, U., Feingold, D.S., Malmström, A. and Rodén, L.
    Biosynthesis of heparin. Assay and properties of the microsomal uronosyl C-5 epimerase.
    J. Biol. Chem. 254: 2975-2982 (1979). [PMID: 107165]
  2. Jacobsson, I., Lindahl, U., Jensen, J. W., Roden, L., Prihar, H., Feingold, D. S.
    Biosynthesis of heparin. Substrate specificity of heparosan N-sulfate D-glucuronosyl 5-epimerase.
    J. Biol. Chem. 259: 1056-1063 (1984). [PMID: 6420398]
  3. Hagner-McWhirter, A., Hannesson, H. H., Campbell, P., Westley, J., Roden, L., Lindahl, U., Li, J. P.
    Biosynthesis of heparin/heparan sulfate: kinetic studies of the glucuronyl C5-epimerase with N-sulfated derivatives of the Escherichia coli K5 capsular polysaccharide as substrates.
    Glycobiology 10: 159-171 (2000). [PMID: 10642607]

[EC created 1984, modified 2015]