Heterogeneity in horse ferritins. A comparative study of surface charge, iron content and kinetics of iron uptake

Abstract

Horse ferritins from different organs show heterogeneity on electrofocusing in Ampholine gradients. Both ferritin and apoferritin from liver and spleen could be fractionated with respect to surface charge by serial precipitation with (NHI4)2SO4. In the ferritin fractions, increasing iron content parallels increasing isoelectric point. After removal of their iron those fractions which originally contained most iron accumulated added iron at the fastest rates. When unfractionated ferritins from different organs were compared the average isoelectric point increased in order spleen< liver< kidney< heart. The order of initial rates of iron uptake by the apoferritins was spleen> kidney> heart and initial average iron contents also followed this order. The relatively low rates of iron accumulation by ironpoor molecules may have been due to structural alteration, to degradation, to activation of the iron-rich molecules or to other factors.

The sedimentation properties of ferritins. New insights and analysis of methods of nanoparticle preparation

“…Evidence linking subunit heterogeneity of HoSF with iron content has been reported previously, although prior to a full understanding of the subunit composition of HoSF [76]. This earlier study reported that the iron content of bands observed in isoelectric focusing correlated with the surface charge of the protein in the bands.…”

“…These results are in agreement with sedimentation results described here. It is interesting to note that the number of bands (~11) observed using isoelectric focusing of various samples [76] corresponds favorably with the number of species calculated from the binomial function (Fig. 11A).…”

“…In our work, s values ranged from 14.3 to 16.7 S for various apoprotein samples prepared from commercially supplied horse spleen ferritin and from protein isolated in our laboratory. This large range reflects oxidative damage to the protein, the tendency of the protein to cross-link to form dimers and higher order oligomers and the inherent heterogeneity associated with the variable subunit composition of the protein itself [49,53,56,57,59,65,76–78]. From s 20, w = 17.0 S, M = 484,120 g/mol and R = 8.3145 × 10 7 erg-K −1 mol −1 , we calculate through $$D_{20,w}=\frac{s_{20,w}·RT}{M·(1-\overline{\nu }{\rho }_{20,w})}$$ Eq.…”

Distinct and Separable Roles of the Complement System in Factor H-Deficient Bone Marrow Chimeric Mice with Immune Complex Disease

“…In contrast, chronic immunization with the highly anionic unmodified apoferritin (46) results in the formation of circulating immune complexes that subsequently deposit in glomeruli, as we have shown in this and previous studies using this model (18,47). In either circumstance, complement depletion or its absence leads to decreased glomerular clearance of immune complexes (34,44,(47)(48)(49), highlighting the relevance and complexities of the complement system in immune complex processing in the glomerulus (3,45).…”

Iron Content of Rat Serum Ferritin.

“…Ferritin is present not only in cells but also in sera, and the serum ferritin level is positively correlated with body iron stores [1-3, 12, 15, 18]. The major function of tissue ferritin is to detoxify and store intracellular iron [8], and it contains a large amount of iron [5,14,17]. Serum ferritin has been found to have different amounts of iron in some mammals [6,9,13,20,22].…”