The Protein Journal

, Volume 24, Issue 7, pp 479–485

Effects of Magnesium Ions on Thermal Inactivation of Alkaline Phosphatase

  • Ying Zhu
  • Xue-Ying Song
  • Wen-Hua Zhao
  • Ying-Xia Zhang

DOI: 10.1007/s10930-005-7643-x

Cite this article as:
Zhu, Y., Song, X., Zhao, W. et al. Protein J (2005) 24: 479. doi:10.1007/s10930-005-7643-x


The effect of Mg2+ on the thermal inactivation and unfolding of calf intestinal alkaline phosphatase has been studied at different temperatures and Mg2+ concentrations. Increasing the Mg2+ concentration in the denatured system significantly enhanced the inactivation and unfolding of the enzyme during thermal inactivation. The analysis of the kinetic course of substrate reaction during thermal inactivation showed that at 47°C the increased free Mg2+ concentration caused the inactivation rate to increase. Increasing the temperature strengthened the effect of Mg2+ on the thermal inactivation. Control experiment showed that this is not due to salt effect. The time course of fluorescence emission spectra showed that the emission maximum for Mg2+-containing system was always higher than that of Mg2+-free system, and the higher temperature enhanced this difference. In addition, Mg2+also enhanced the unfolding rate of the enzyme at 47°C. The potential biological significance of these results are discussed.


Alkaline phosphatasemagnesium ionthermal inactivation



calf intestinal alkaline phosphatase


alkaline phosphatase


p-nitrophenyl phosphate


magnesium acetate


regression coefficient.

Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  • Ying Zhu
    • 1
  • Xue-Ying Song
    • 1
  • Wen-Hua Zhao
    • 1
  • Ying-Xia Zhang
    • 1
    • 2
  1. 1.Department of Chemical BiologyCapital University of Medical SciencesBeijingP. R. China
  2. 2.Laboratory for Liver Protection and Regulation of Capital University of Medical SciencesChina