Reconstitution studies of Ferritin iron cores

Reconstitution experiments were conducted to study the effect of temperature, reaction rate, and phosphate on the nature and behavior of ferritin iron cores. Reconstitution of ferritin iron cores at 4°C and 55°C showed that reconstitution at the higher temperature resulted in the formation of cores that are more ordered and larger than cores reconstituted at the lower temperature as confirmed by transmission electron microscopy, electron diffraction, and Mossbauer spectroscopy. The results were explained in terms of the relationship between temperature and particle growth. The addition of Fe(II) in one step during the course of reconstitution produced cores that are smaller in size and less ordered than cores of ferritins reconstituted by the gradual addition of small numbers of Fe atoms over an extended period of time. These results confirm the long-standing presumption that a higher rate of iron uptake results in the formation of less-ordered cores. A kinetics study showed that phosphate increased the rate of nucleation of the ferritin iron cores but hindered crystal growth. The reconstitution of ferritin in the presence of phosphate used three methods of Fe and phosphate addition. UV-visible spectrophotometric results indicated that to form cores where phosphate can be incoporated within the cores, the phosphate has to be added before or alternately with Fe. A model by which bacterial ferritin iron cores are formed was formulated