Mg2+ binding affects the structure and activity of ovomucin

Metal-protein interaction for regulating the function and structure of proteins is of major interest. We demonstrate here that the addition of 9 μmol Mg2+ per mg ovomucin resulted in a 2.0-fold increase in the adhesion capacity of ovomucin to New Disease Virus (NDV) using ELISA method. The hemagglutinin inhibition rate of 100 μg/mL ovomucin-Mg2+mixture (9 μmol Mg2+ per mg ovomucin) to NDV increased to 55.61%, which is significantly higher than that of the pure ovomucin (P < 0.01). Binding characteristics of ovomucin to Mg2+ were then evident by fluorescence and FT-IR spectroscopy as well as dynamic light scattering (DLS) technology. Fluorescence and FT-IR spectroscopy results suggest that Mg2+ prefers to interact with the carbohydrate moiety of ovomucin without significant changes in the secondary structure when Mg2+ concentration is less than 9 μmol/mg ovomucin. When Mg2+ increases to 16 μmol/mg ovomucin, it gives rise to changes in secondary structure, and forms a more compact configuration. This is supported by the hydrodynamic radius of ovomucin with and without Mg2+ binding as examined by DLS. The Mg2+ bound in regulating the structure and activity of ovomucin provided important insight into the effect of metal ions on ovomucin binding to pathogens.