Iron release

Rice-Evans, C., Okunade, G. and Khan, R. (1989). The suppression of iron release from activated myoglobin by physiological electron donors and desferrioxamine. Free Rad. Res. Commun. 7, 45-54. 

Rice-Evans, C., Green, E., Paganga, G., Cooper, C. and Wri esworth, J. (1993). Oxidised low density lipoproteins induce iron release from activated myoglobin. FEBS Lett. 326, 177-182. 

Biemond, P., Swaak, A.J.G., van Eijk, H.G. and Koster, J.F. (1988). Superoxide-dependent iron release from ferritin in inflammatory diseases. Free Rad. Biol. Med. 4, 185-198. 

Figure 9.6 Iron release from monocytes after erythrophagocytosis. Relative release (%) of [59Fe]iron molecular species from monocytes (MN) during the first 24 hours following erythrophagocytosis. MN from patients with hereditary haemochromatosis (right) take up fewer red blood cells (RBC) and released more 59Fe as low-molecular-weight (LMW) complexes as compared with MN from normal controls (left).

One aspect of microbial iron metabolism that remains unclear in many cases is the mechanism for iron release from tight sequestration once the siderophore complex arrives at its... 

Another possible route for reduction of the iron center is photoreduction. This has been studied in a variety of marine siderophore systems, such as aquachelin, marinobactin, and aerobactin (2), where it was demonstrated that photolytic reduction was due to a ligand-to-metal charge transfer band of the Fe(III)-siderophore complex, eventually resulting in reduction ofiron(III) and cleavage of the siderophore (31,154,155). This suggests a possible role for iron reduction in iron release (71,155). 

The release of iron from ferritin can be induced by different factors. In 1984, Biemond et al. [159] have shown that stimulated leukocytes mobilize iron from human and horse ferritin. Release of iron was induced by superoxide because SOD inhibited this process. Similarly, the release of iron from ferritin can be induced by xanthine oxidase [160] this process is believed to induce ischemia and inflammation. Under anerobic conditions xanthine oxidase is also able to stimulate iron release from ferritin through superoxide-independent mechanism [161]. Another physiological free radical nitric oxide also stimulates iron release from ferritin [162],... 

It is known that erythrocytes from patients with sickle cell anemia contain various types of abnormal iron deposits [398], which could be the origin of the overproduction of oxygen radicals in these cells. Indeed, Hebbel et al. [399] has showed that sickle erythrocytes spontaneously generate approximately twice as much superoxide as normal erythrocytes. Later on, it has been shown that these cells are also able to generate hydroxyl radicals catalyzed by three types of iron, preexisting free iron, free iron released during oxidative stress, and iron that cannot be chelated with desferrioxamine [400]. 

Reelfs, O., Tyrrell, R. M., and Pourzand, C., Ultraviolet a radiation-induced immediate iron release is a key modulator of the activation of NF-kappaB in human skin fibroblasts, J. Invest. Dermatol. 122, 1440-1447, 2004. 

Wolz, C., Hohloch, K., Ocaktan, A., Poole, K., Evans, R. W., Rochel, N., Albrecht-Gary, A.-M., Abdallah, M. A. and Doering, G. (1994). Iron release from transferrin by pyoverdin and elastase from Pseudomonas aeruginosa, Infect. Immunol., 62, 4021 -027. 

The importance of iron for a bacteria-like E. coli can be illustrated by fact that 14 genes alone are required for enterobactin-mediated iron uptake, including those for its synthesis, export, transport of the ferric-enterobactin back into the cell and iron release (Figure 3.16). In total, E. coli has at least 8 uptake systems for iron, encoded by some 50 genes. 

Mason, A.B., Halbrooks, P.J., James, N.G., Connolly, S.A., Larouche, J.R., Smith, V.C., MacGillivray, R.T.A. and Chasteen, N.D. (2005) Mutational analysis of C-lobe ligands of human serum Transferrin insights into the mechanism of iron release, Biochemistry, 44, 8013-8021. 

MacGillivray, R.T., Moore, S.A., Chen, J., Anderson, B.F., Baker, H., Luo, Y., Bewley, M., Smith, C.A., Murphy, M.E., Wang, Y., Mason, A.B., Woodworth, R.C., Brayer, G.D. and Baker, E.N. (1998) Two high-resolution crystal structures of the recombinant N-lobe of human transferrin reveal a structural change implicated in iron release, Biochemistry, 37, 7919-7928. 

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