title: Purification and characterization of thermostable xylose(glucose) isomerase from Bacillus thermoantarcticus.
abstract: Xylose isomerase produced by Bacillus thermoantarcticus was purified 73-fold to homogeneity and its biochemical properties were determined. It was a homotetramer with a native molecular mass of 200 kDa and a subunit molecular mass of 47 kDa, with an isoelectric point at 4.8. The enzyme had a K(m) of 33 mM for xylose and also accepted D-glucose as substrate. Arrhenius plots of the enzyme activity of xylose isomerase were linear up to a temperature of 85 degrees C. Its optimum pH was around 7.0, and it had 80% of its maximum activity at pH 6.0. This enzyme required divalent cations for its activity and thermal stability. Mn(2+), Co(2+) or Mg(2+) were of comparable efficiency for xylose isomerase reaction, while Mg(2+) was necessary for glucose isomerase reaction.
authors.affiliation: Istituto per la Chimica di Molecole di Interesse Biologico, CNR, Via Campi Flegrei, 34, Pozzuoli 80078 (Na), Italy.
authors.forename: L
authors.initials: L
authors.lastname: Lama
authors.forename: B
authors.initials: B
authors.lastname: Nicolaus
authors.forename: V
authors.initials: V
authors.lastname: Calandrelli
authors.forename: I
authors.initials: I
authors.lastname: Romano
authors.forename: R
authors.initials: R
authors.lastname: Basile
authors.forename: A
authors.initials: A
authors.lastname: Gambacorta
mesh_terms: D019747:Aldose-Ketose Isomerases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology*; D001709:Biotechnology / Q000379:methods; D003470:Culture Media; D004795:Enzyme Stability; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007700:Kinetics
chemical_list: D003470:Culture Media; D019747:Aldose-Ketose Isomerases; C023298:xylose isomerase