D-Xylose (D-glucose) isomerase from Arthrobacter strain N.R.R.L. B3728. Purification and properties

Biochem J. 1991 Jul 1;277 ( Pt 1)(Pt 1):255-61. doi: 10.1042/bj2770255.


D-Xylose (D-glucose) isomerase was purified to homogeneity in yields of approx. 1 g/kg of wet cells from a strain of Arthrobacter that produces it as about 10% of total soluble protein. It is a tetramer of identical 43,114 Da subunits containing a preponderance of acidic residues and no cysteine. Partial protein sequences were determined as a step to gene cloning. It requires Mg2+, Co2+ or Mn2+ for activity, Mg2+ being best; Ca2+ is an inhibitor, competitive with Mg2+. It is a good D-glucose isomerase with kcat. 1200 min-1 at pH 8 at 60 degrees C, which is higher than that of any other enzyme of this class. L-Arabinose, D-ribose and D-lyxose are poor substrates, with kcat. 78, 31 and 3.7 min-1 respectively at pH 8 at 30 degrees C, compared with 533 min-1 for D-xylose. Xylitol is a true competitive inhibitor for D-xylose (Ki 0.3 mM), but D-sorbitol shows mixed inhibition (Ki 6.5 mM). For D-fructose the pH optimum at 60 degrees C is 8, and at pH 7 the Arrhenius activation energy is 75 kJ/mol over the range 30-70 degrees C.

MeSH terms

  • Aldose-Ketose Isomerases*
  • Amino Acid Sequence
  • Amino Acids / analysis
  • Arthrobacter / enzymology*
  • Bacteria / enzymology
  • Carbohydrate Epimerases / isolation & purification*
  • Carbohydrate Epimerases / metabolism
  • Cations, Divalent
  • Chromatography, Gel
  • Electrophoresis, Polyacrylamide Gel
  • Kinetics
  • Macromolecular Substances
  • Molecular Sequence Data
  • Molecular Weight
  • Peptide Fragments / isolation & purification
  • Substrate Specificity
  • Trypsin


  • Amino Acids
  • Cations, Divalent
  • Macromolecular Substances
  • Peptide Fragments
  • Trypsin
  • Carbohydrate Epimerases
  • Aldose-Ketose Isomerases
  • xylose isomerase