HEN EGG-WHITE LYSOZYME-METAL ION INTERACTIONS - INVESTIGATION BY ELECTROSPRAY-IONIZATION MASS-SPECTROMETRY

The present paper reports the first investigation of HEL interactions with metal ions using a powerful technique, namely electrospray ioniza tion mass spectrometry (ESI-MS). The protonation states are the same w ith a HEL-metal ion mixture as with HEL taken alone. HEL binds from 1 to 8 ions of Cu2+, where the ratios of Cu2+ varied from 1 to 86 ions o f Cu2+ per molecule of HEL within the mixture. HEL was also able to bi nd from 1 to 6 ions of Zn2+ when the ratio of this metal ion varied in the same manner as copper. No effect on the enzyme activity was provo ked by Cu2+ or Zn2+.