d-Glucose/xylose isomerase from Streptomyces: Differential roles of magnesium and cobalt ions
1992; Elsevier BV; Volume: 14; Issue: 4 Linguagem: Inglês
10.1016/0141-0229(92)90158-k
ISSN1879-0909
AutoresSushama M. Gaikwad, Mala B. Rao, Vasanti Deshpande,
Tópico(s)Metabolism, Diabetes, and Cancer
ResumoThe presence of Mg2+ and Co2+ is essential for the maximum activity of glucose/xylose isomerase (GXI) from Streptomyces sp. NCIM 2730. Mg2+ is superior to Co2+ as an activator but fails to protect the enzyme against inactivation by denaturants. The inactivation of GXI by urea, guanidinium chloride, heat, and acid pH is protected by Co2+. Thermal dissociation of the active dimer into inactive monomer was partly prevented by Co2+, suggesting that Co2+ has an essential role in holding the ordered conformation, especially the quaternary structure of the enzyme.
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