H₂-Uptake Activity, Spectra, Reduction Potentials, and Kinetics of Iron Release on the Surface of Iron Core from Azotobacter vinelandii Bacterial Ferritin

Abstract

Bacterial ferritin from Azotobacter vinelandii (AvBF_o has a function in H₂ uptake. The Fe³⁺ reduction on the surface of the iron core from AvBF_o is accompanied simultaneously by H₂ uptake, with a maximum activity of H₂ uptake of 450 H₂/AvBF_o. A reduction potential of −402 mV for iron reduction on the surface of the core is found. A shift to the red the protein absorbance peaks ranging from 280 to 290 nm is observed between pH5 and 9 under 100% H₂ reduction. The reduction potential for iron release becomes negative at a rate of 0.025 mV/Fe²⁺ released. The kinetics of iron release on the surface of the core is a first-order reaction.