DYNAMIC AND STRUCTURAL-PROPERTIES OF GLUCOSE-OXIDASE ENZYME

The catalytic oxidation of beta-D-glucose by the enzyme glucose oxidas e involves a redox change of the flavin coenzyme. The structure and th e dynamics of the two extreme glucose oxidase forms were studied by us ing infrared absorption spectroscopy of the amide I' band, tryptophan fluorescence quenching and hydrogen isotopic exchange. The conversion of FAD to FADH(2) does not change the amount of alpha-helix present in the protein outer shell, but reorganises a fraction of random coil to beta-sheet structure. The dynamics of the protein interior vary with the redox states of the flavin without affecting the motions of the st ructural elements near the protein surface. From the structure of gluc ose oxidase given by X-ray crystallography, these results suggest that the dynamics of the interface between the two monomers are involved i n the catalytic mechanism.