Study of the Dynamic Structure of Native and Hydrophobized Glucose Oxidase by Time-Domain Dielectric Spectroscopy

The dynamic structures of native and hydrophobized (by covalent attachment of palmitoyl chains) glucose oxidase were studied by time-domain dielectric spectroscopy (TDDS). Analysis of the dipole correlation function for both types of the enzyme showed that the decay of the correlation function of the macromolecule motion can be presented as a sum of components corresponding to different kinds of protein motion:  isotropic rotation of the protein molecule as a whole, anisotropic Brownian tumbling of subunits, and anisotropic intramolecular motion of polar groups and substructures. The slowest relaxation time was found to be longer for the modified enzyme than for the native enzyme. The dielectric strengths for all relaxation processes, as well as the dipole moment and the molecular volume, were also larger for the modified glucose oxidase. The observed differences between various types of the dipole motion for the native and modified glucose oxidase are discussed.