Iron and phosphorus content of rabbit liver ferritin fractions with different subunit composition

After isolation of subtypes of rabbit liver-ferritin, the phosphorus to iron ratio (P/Fe-ratio) in the samples was found to parallel the shift in subunit composition of the two types of subunits of which ferritins generally consist. No relation was found with the amount of iron per ferritin molecule. The increase of the P/Fe-ratio, in relation to subunit composition, is postulated to be a result of the change of total surface area of the iron microcrystallites inside the ferritin molecule. This surface area depends on the number of nucleation points and thereby may be dependent on the subunit composition.