Print Email Facebook Twitter Inhibition and stimulation of formation of the ferroxidase center and the iron core in Pyrococcus furiosus ferritin Title Inhibition and stimulation of formation of the ferroxidase center and the iron core in Pyrococcus furiosus ferritin Author Honarmand Ebrahimi, K. Hagedoorn, P.L. Hagen, W.R. Faculty Applied Sciences Department Biotechnology Date 2010-06-26 Abstract Ferritin is a ubiquitous iron-storage protein that has 24 subunits. Each subunit of ferritins that exhibit high Fe(II) oxidation rates has a diiron binding site, the socalled ferroxidase center (FC). The role of the FC appears to be essential for the iron-oxidation catalysis of ferritins. Studies of the iron oxidation by mammalian, bacterial, and archaeal ferritin have indicated different mechanisms are operative for Fe(II) oxidation, and for inhibition of the Fe(II) oxidation by Zn(II). These differences are presumably related to the variations in the amino acid residues of the FC and/or transport channels. We have used a combination of UV–vis spectroscopy, fluorescence spectroscopy, and isothermal titration calorimetry to study the inhibiting action of Zn(II) ions on the iron-oxidation process by apoferritin and by ferritin aerobically preloaded with 48 Fe(II) per 24-meric protein, and to study a possible role of phosphate in initial iron mineralization by Pyrococcus furiosus ferritin (PfFtn). Although the empty FC can accommodate two zinc ions, binding of one zinc ion to the FC suffices to essentially abolish iron-oxidation activity. Zn(II) no longer binds to the FC nor does it inhibit iron core formation once the FC is filled with two Fe(III). Phosphate and vanadate facilitate iron oxidation only after formation of a stable FC, whereupon they become an integral part of the core. These results corroborate our previous proposal that the FC in PfFtn is a stable prosthetic group, and they suggest that its formation is essential for iron-oxidation catalysis by the protein. Subject ferritinferroxidase centeriron oxidationisothermal titration calorimetryphosphate To reference this document use: http://resolver.tudelft.nl/uuid:d33831f5-8edc-4290-95eb-a4f42ffdcee3 DOI https://doi.org/10.1007/s00775-010-0682-6 Publisher Springer ISSN 0949-8257 Source Journal of Biological Inorganic Chemistry, June 26, 2010 Part of collection Institutional Repository Document type journal article Rights (c) 2010 The Author(s) Files PDF Honarmand_2010.pdf 878.81 KB Close viewer /islandora/object/uuid:d33831f5-8edc-4290-95eb-a4f42ffdcee3/datastream/OBJ/view