Ferritin properties

Finally, animal, plant and microbial tissues have been shown to contain the iron storage protein ferritin. The animal protein has been extensively studied, but the mechanism of iron binding has not been completely resolved (29). Animal tissues contain, in addition, a type of granule comprised of iron hydroxide, polysaccharide and protein. The latter, called hemosiderin, may represent a depository of excess iron (30). Interestingly, a protein with properties parallel to those of ferritin has been found in a mold. Here the function of the molecule can be examined with the powerful tools of biochemical genetics (31). 

Su, M., Cavallo, S., Stefanini, S., Chiancone, E. and Chasteen, N.D. (2005) The so-called Listeria inocua ferritin is a Dps protein. Iron incorporation, detoxification and DNA protection properties. Biochemistry, 44, 5572-5578. 

CNTs can be processed such as purification based on oxidation, cutting, and activation by forming carboxylic acid and hydroxyl groups on the surface of CNTs, which can further be linked with other biomolecules to realize special function (Ajayan et al., 1994). As shown in Fig. 9.19, ferritin molecules attached to the surface of CNTs via covalent bond, the nanocomposites with ferritin molecules-functionalized CNTs own better mechanical, thermal, and electronic properties... 

Different Mossbauer and magnetometric studies have shown the superparamagnetism of ferritin iron cores. This property is also typical of ferro-... 

The problems to be solved are listed hereafter the first problem is the lack of data concerning the exact proportions of low-molecular weight iron complex, ferritin-bound iron and hemosiderin-bound iron (54). However, transverse NMRD profiles of iron-loaded tissues indicate that the transverse relaxation is essentially caused by ferritin, because of the linearity between I/T2 and Bq, which is a fingerprint of ferritin-induced relaxation. The relaxation properties of hemosiderin are less understood. If the proportion of ferritin and hemosiderin is not the same in all of the studied tissues, the correlation between the relaxation properties and the total iron concentration could be affected. 

There is a number of synthetic substitutes for natural ferritin and the properties of these have been compared with those of ferritin. The synthetic polysaccharide iron complex (PIC), has a magnetic blocking temperature of 48K (Mohie-Eldin et al. 1994). Iron-dextran complexes are used as a substitute for ferritin in the treatment of anaemia. The iron cores of these complexes consist not of ferrihydrite, but of very poorly crystalline akaganeite with magnetic blocking temperatures of between 150 and 290 K (Muller, 1967 Knight et al. 1999) which were lowered from 55K to 35 and 25K, if prepared in the presence of 0.250 and 0.284 Al/(A1 -i- Fe), respectively (Cheng et al.2001). 

R.E. Spitzer, C.R. (1977) The Viking magnetic properties experiment Primary mission results. J. Geophys. Res. 82 4547-4558 Harrison, J.B. Berkheiser,V.E. (1982) Anion interactions with freshly prepared hydrous iron oxides. Clays Clay Min. 30 97-102 Harrison, P.M. HoyT.G. (1973) Ferritin. In Eichhom, G.L. (ed.) Inorganic biochemistry. 

Biotin is a small vitamin molecule (Mr 244) that binds with highaffinity (kD 10 I5M I) to avidin. Avidin is a larger glycoprotein molecule (Mr 70,000), mostly distributed in egg whites. This protein has the advantage of conjugating with different markers, including peroxidase, fluorescent dyes, colloidal gold, and ferritin. Because of this property it is... 

St. Pierre, T. G. Chan, R Bauchspiess, K. R. Webb, J. Betteridge, S. Walton, S. Dickson, D. P. E. Synthesis, structure and magnetic properties of ferritin cores with varying composition and degrees of structural order models for iron oxide deposits in iron-overload diseases. Coord. Chem. Rev. 1996, 151, 125-143. 

Antibody molecules cannot be seen with the light microscope unless they are labeled. A variety of labels have been used including fluorescent compounds and their active enzymes, all with the property of inducing the formation of a colored reaction product from a suitable substrate system to allow visualization. Some of these systems can be employed in electron microscopy by rendering the reaction product electron dense through appropriate treatment. Alternatively, particulate labels such as gold, ferritin, or viral particles can be used (Leong 1993). 

A low molecular weight protein, different from metallothionine which reversibly binds iron with high affinity has been isolated from rabbit reticulocyte cytosol (54, 55, 56). Although very little is yet known about its physiological properties, the molecular weight is around 6000, and iron appears to be reversibly bound under physiological conditions. This protein may be able to mobilize iron from the plasma membrane and donate it for heme and ferritin biosynthesis (56), but no definitive physiological role for siderochelin has been established. 

---