Kinetics of iron reduction of ferritin cores and of a low molecular weight hydroxy-iron polymer.
The kinetics of reduction by dithionite of iron cores in ferritin and of iron cores after removal of the protein shell (isolated cores) has been analysed along with that of a low molecular weight hydroxy-iron polymer. Spectrophotometric measurements have shown that the time course of the reaction approximates a pseudo first-order behaviour. In the case of ferritin cores the pseudo first-order rate constant reaches an asymptotic value which markedly increases when the cores are isolated. In contrast, in the low molecular weight hydroxy-iron polymer, no clear asymptotic value is reached. Thus, the rate of reduction appears to be determined both by the presence of the protein shell and by the crystallite surface area. Kinetic light scattering experiments show that in ferritin and in the isolated cores a rapid drop in molecular weight occurs during the first stages of reduction, suggesting a fragmentation of the iron crystallite.
D005293:Ferritins; D007501:Iron; D007700:Kinetics; D008970:Molecular Weight; D010084:Oxidation-Reduction; D011108:Polymers; D013053:Spectrophotometry
D011108:Polymers; D005293:Ferritins; D007501:Iron