Effects of metal ions on the activity of protein tyrosine phosphatase VHR: highly potent and reversible oxidative inactivation by Cu2+ ion

Arch Biochem Biophys. 2000 Oct 1;382(1):72-80. doi: 10.1006/abbi.2000.1996.


The posttranslational regulation of protein tyrosine phosphatases (PTPs) has been suggested to have a crucial role in maintaining the phosphotyrosine level in cells. Here we examined the regulatory effects of metal ions on human dual-specificity vaccinia H1-related protein tyrosine phosphatase (VHR) in vitro. Among various metal ions examined, Fe3+, Cu2+, Zn2+, and Cd2+ exerted their inactivational effects on VHR, and Cu2+ is the most potent inactivator. The VHR activity inactivated by the metal ions except Cu2+ was significantly restored by EDTA. The efficacy of Cu2+ for the VHR inactivation was about 200-fold more potent than that of H2O2. Cu2+ also inactivated other PTPs including PTP1B and SHP-1. The Cu2+-mediated inactivation at the submicromolar range was eradicated by dithiothreitol treatment. The loss of VHR activity correlated with the decreased [14C]iodoacetate labeling of active-site cysteine, suggesting that Cu2+ brought about the oxidation of the active-site cysteine. On the contrary, Zn2+ that exerted an inactivational effect at millimolar concentrations appeared not directly linked to the active-site cysteine, as indicated by the fact that [14C]iodoacetate labeling was unaffected and that the effect of Zn2+ on the Y78F mutant was increased. The reduction potential of VHR was estimated to be -331 mV by utilizing the reversibility of the redox state of VHR. Thus, we conclude that the highly potent Cu2+ inactivation of VHR is a consequence of the oxidation of the active-site cysteine and the mode of Zn2+ inactivation is distinct from that of Cu2+.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Copper / metabolism*
  • Cysteine / chemistry
  • Dithiothreitol / pharmacology
  • Dose-Response Relationship, Drug
  • Dual Specificity Phosphatase 3
  • Electrophoresis, Polyacrylamide Gel
  • Enzyme Activation
  • Glutathione / metabolism
  • Hydrogen Peroxide / pharmacology
  • Ions*
  • Mass Spectrometry
  • Models, Chemical
  • Mutagenesis, Site-Directed
  • Oxygen / metabolism*
  • Protein Tyrosine Phosphatases / antagonists & inhibitors
  • Protein Tyrosine Phosphatases / metabolism*
  • Time Factors
  • Zinc / metabolism


  • Ions
  • Copper
  • Hydrogen Peroxide
  • DUSP3 protein, human
  • Dual Specificity Phosphatase 3
  • Protein Tyrosine Phosphatases
  • Glutathione
  • Zinc
  • Cysteine
  • Oxygen
  • Dithiothreitol