Mode of Inhibition of Glucose Oxidase by Metal Ions

概要

論文の詳細を見る
1. The reaction catalyzed by the glucose oxidase [EC 1. 1. 3. 4] from Aspergillus niger was markedly inhibited by Ag+, Hg++, Cu++, PCMB and PMA, but not by non-metallic SH-reagents, such as NEM, IA and IAA. No sulfhydryl group was detected in the enzyme protein by spectrophotometric titration with PCMB and NEM. Characteristic difference spectra due to the absorption by the FAD moiety of the enzyme were obtained on the addition of Ag+, Hg++, Cu++, PCMB and PMA to enzyme solutions while no spectral change was observed on the addition of other metal ions and NEM, which did not inhibit the enzyme reaction. 2. From the studies by overall reaction kinetics and the "flow method", it was confirmed that Ag+ and Hg++ ions inhibit the oxidation of the reduced FAD moiety, competing with molecular oxygen used as a hydrogen acceptor. While Ag+ ion did not inhibit the reduction of the FAD moiety, Hg++ ion more or less inhibited the reduction described above. It was suggested that there is an interaction, probably by steric hindrance, between the substrate and the Hg++ ion for binding to the enzyme molecule. From the kinetic data obtained in the presence of both Ag+ and Hg++ ions, it was concluded that the binding sites for these two kinds of metal ions on the enzyme molecule are different.
社団法人日本生化学会の論文